🔬 Glossary of Bacteriophage Terms

Phage Biology and Phage Therapy Terminology Defined and Discussed

by Stephen T. Abedon Ph.D. (abedon.1@osu.edu)

phage.org | phage-therapy.org | biologyaspoetry.com | abedon.phage.org | google scholar

Jump to:   ℹ️ About  |  📖 Glossary  |  🦠 Immunity  |  🔢 Multiplicity  |  🧫 Plaques  |  📋 Project  |  🧮 Calculators

phage.org/terms/  ·  Abedon’s Books  ·  DOI: 10.5281/zenodo.20173633

How can I improve this page?  contact: terms@phage.org

ℹ️ About This Glossary

The Glossary of Bacteriophage Terms is an ongoing project of phage.org, the Bacteriophage Ecology Group. Its goal is to provide definitions and discussions of terminology used in phage biology and phage therapy, with links to related terms and, especially, older literature that can be used to help define these terms.

The glossary has been developed in stages. The original term pages were created between 2011 and 2012 and hosted at archaealviruses.org/terms/. Those pages are now being converted to the current format at phage.org/terms/, with expanded discussions and systematic linking throughout.

A companion manuscript has been published as a preprint:

Abedon, S.T. (2025). Phage Therapy Annotated Glossary. Preprints.org. 10.20944/preprints202508.0347.v1

Terms with fully developed pages are listed in the 📖 Glossary tab. The 📋 Project tab preserves the original master term list — including the several hundred terms not yet developed — so that the full scope of the project remains visible. Thematic sub-lists covering immunity, multiplicity, and plaque terminology appear in their own tabs.

How to Cite

Abedon, S.T. (2026). Phage Terms. https://terms.phage.org  ·  10.5281/zenodo.20173633

📖 Glossary — Alphabetical Index

Terms with fully developed pages. See the 📋 Project tab for the complete master list including undeveloped terms.

Loading terms…

For more phage terms, see Abedon, S.T. (2025). Phage Therapy Annotated Glossary. Preprints.org. 10.20944/preprints202508.0347.v1

How to Cite

Abedon, S.T. (2026). Phage Terms. https://terms.phage.org  ·  10.5281/zenodo.20173633

🦠 Immunity Terms

Terms associated with the concept of temperate phage immunity. Linked terms have developed pages; unlinked terms (italic grey) are not yet developed.

  • Little, J.W. (2005). In: Phage Lambda and Its Relatives. Cold Spring Harbor Laboratory Press.
  • Ptashne, M. (2004). A Genetic Switch. 3rd ed. Cold Spring Harbor Laboratory Press.

🔢 Multiplicity Terms

Terms associated with the concept of phage multiplicity. Linked terms have developed pages; unlinked terms (italic grey) are not yet developed.

Adsorption
Adsorption (rate) constant
Adsorption rate
Bound free phage
Capacity
Coinfection
Free phage
Infected bacteria
Infection
Irreversible adsorption
Killing titer
Lysis from without
Mass action
MOIactual
MOIinput
Multiple adsorption
Multiple infection
Multiplicity of adsorption
Multiplicity of infection (MOI)
Poisson distribution
Residual fraction
Saturation
Secondary adsorption
Secondary infection
Single infection
Superinfection
Target bacteria
Titer
Virus particle

🧫 Plaque Terms

Terms associated with the concept of plaques and their formation. Linked terms have developed pages; unlinked terms (italic grey) are not yet developed.

📋 Project — Master Term List

The complete scope of the Glossary of Bacteriophage Terms project. Linked terms have developed pages; unlinked terms (grey) are planned but not yet developed.

Key: (G) = glossary manuscript  ·  (GG) = Glossary of Genetics  ·  (IT) = Immunity Terms  ·  (MT) = Multiplicity Terms  ·  (PT) = Plaque Terms  ·  (MPD) = Mycobacteriophage Glossary
A
Abortive infection (Abi)
Absolute efficiency of plating (PT)
Abortive transduction (GG)
Absolute burst size
Active penetration (G)
Actinophage
Active-passive treatment
Active phage therapy
Active treatment
Adolescent period
Adsorption (MT)
Adsorption affinity
Adsorption capacity
Adsorption cofactor
Adsorption (rate) constant (MT)
Adsorption efficiency
Adsorption media
Adsorption protein
Adsorption rate (MT)
Adsorption resistance
Adsorption synchronization (G)
Adult period (G)
Alysogeny (GG)
Amber mutation (GG)
Amplification (G)
Antiholin
Anti-phage serum
Anti-receptor
Antirestriction
Antitermination (GG)
Aptitude
Archaeal virus (G)
Artificial lysis
Assembly (virion)
Attachment
Attachment protein
Attachment site
Autolysis
Autophage
Average burst size
B
Baseplate
Bacteria-like phage population growth (G)
Bacteria-like phage survival properties (G)
Bacterial resistance to phages (G)
Bacterial virus
Bacteriocin
Bacteriocynogeny
Bacteriolysant
Bacteriophagum intestinal
Binary phage
Bacteriophage (MPD)
Bacteriophage-insensitive mutants (BIMs)
Biocontrol (G)
Blue whale unit
Bound free phage (MT)
Bred phage
Budding (G)
Bull’s eye plaque (PT)
Burst
Burst size (MPD)
C
Campbell model (GG)
Capacity (MT) (PT)
Capsid (MPD)
Capsomere (GG)
Capsule
Carrier state (G)
Caudovirales
Chronic infection
Chronically infecting phage
Chronic release
cI / CI (IT)
CI repressor (IT)
cII / CII (IT)
Clear mutant (IT) (PT)
Clear plaque (IT) (PT)
Clear-plaque mutant (IT) (PT)
Cocktail (phage cocktail)
Coinfection (IT) (MT)
Coliphage
Complete phage particle
Confluent lysis (PT)
Constant period
CRISPR
Cro
Crude lysate
Cryptic prophage
Culture lysis
D
Defective prophage
Depressor effect
Destructive infection (IT)
d’Hérelle (1917)
d’Hérelle phenomenon
Diffusion (PT)
Direct-plating plaquing method (PT)
Double agar overlay (PT)
Double-overlay plaquing method (PT)
Divalent cation
DNA modification
E
Early gene
Eclipse
Effective burst size
Efficiency of center of infection (ECOI) (PT)
Efficiency of infection
Efficiency of plating (EOP) (PT)
Encounter
End-point determination
Endolysin
Enzybiotic
EPS depolymerase (PT)
Extracellular search
Extrusion
F
Foreign genes
Filamentous phage
Free phage (MT)
G
Generalized transduction
Ghost
Hard times hypothesis
H
Head (MPD)
Heteroimmune (IT)
High molecular weight bacteriocin
High molecular weight pyocin
Holin
Homoimmune (MPD) (IT)
Host enzyme
Host-genome degradation
Host range
Host range broadening
Host range narrowing
Host-range switch
Host-lethal protein
Host-range expansion
I
Immediate lytic cycle
Immediate lytic infection
Immediately productive
Immunity (IT)
Immunity group (IT)
Immunity region (IT)
Immunity to ghosts
Immunity type (IT)
Inactivation
Incomplete phage particle
Indicator bacteria (PT)
Induced lytic cycle
Induced lytic infection
Induced productive infection
Inducing agent
Induction
Infected bacteria (MT)
Infection (MT)
Infection vigor
Infectious center (PT)
Infective center (PT)
Injection
Inoviridae
Insertion
Insertion site
Intemperate
Inundative treatment
Irreversible adsorption (MT)
J–K
Juvenile period
Killing the winner
Killing titer (MT)
Kinetic determination
L
Lambda repressor
Lambdoid phages
Late gene
Latent period
Lateral tail fiber
Lawn (PT)
Liberation
Long tail fiber
Lysate
Lysin
Lysis
Lysis curve
Lysis from within
Lysis from without
Lysis inhibition (PT)
Lysis inhibition collapse
Lysis profile
Lysis timing
Lysogen (MPD) (IT)
Lysogenic
Lysogenic bacterium
Lysogenic conversion
Lysogenic culture
Lysogenic cycle (MPD) (IT)
Lysogenic infection (IT)
Lysogenic phage
Lysogenic state (IT)
Lysogenization (IT)
Lysogeny
Lysozyme
Lytic cycle (MPD)
Lytic infection
Lytic-lysogeny decision (IT)
Lytic phage
M
Mass action (MT)
Maturation
Maturation period
Mature virion
Microbe-mediated biocontrol
Microcolony (PT)
Minimum latent period
Mixed-indicator method (PT)
Mixed infection
MOIᴀᴄᴛᵁᴀʟ (MT)
MOIᴵᴿᴿᵁᴛ (MT)
Monophage
Monovalent cation
Moron
Moron acquisition
Multiple adsorption (MT)
Multiple infection (MT)
Multiplicity of adsorption (MT)
Multiplicity of infection (MT)
Mutual exclusion
Mycobacteriophage (MPD)
Myoviridae (MPD)
N–O
Nonreceptive bacterium
Numerical refuge
Obligately chronic infection
Obligately chronic phage
Obligately lytic infection
Obligately lytic phage
Obligately productive cycle
Obligately productive infection
Obligately productive phage
One-step growth
P
Packaging
Parental cell
Parental infection (PT)
Parental phage
Passive phage therapy
Passive treatment
Permissive host
Phage (MPD)
Phages
Phage-based biocontrol
Phage CTXΦ
Phage course
Phage cross experiments
Phage display
Phage ecology
Phage-escape mutant
Phage exclusion
Phage gene
Phage genome
Phage history
Phage host
Phage lambda (λ)
Phage M13
Phage particle
Phage population
Phage population growth (PT)
Phage progeny
Phage receptor
Phage-resistant bacteria
Phage-sensitive bacteria
Phage-susceptibility type
Phage-susceptible bacteria
Phage T1–T7
Phage therapy
Phage type
Phage typing (PT)
Phage virulence
Phagologist
Plaque (MPD) (PT)
Plaque count (PT)
Plaque fecundity (PT)
Plaque formation (PT)
Plaque-forming ability (PT)
Plaque-forming unit (PT)
Plaque halo (PT)
Plaque morphology (PT)
Plaque productivity (PT)
Plaque yield (PT)
Plasmid prophage
Podoviridae (MPD)
Poisson distribution (MT)
Polylysogeny (IT)
Polyphage
Portal (MPD)
Post eclipse
Preadsorption (PT)
Primary adsorption
Primary infection
Productive infection
Productive cycle
Professionally lytic
Prophage (IT)
Prophage cured
Prophage excision
Premature lysis
Pseudolysogenic state
Pseudolysogenic infection
Pseudolysogeny
R
Rapid lysis
Rapid lysis mutant
Reaction-diffusion (PT)
Receptor affinity
Receptor binding domain
Reduced infection vigor (PT)
Reduction to a prophage
Reductive infection
Relative efficiency of plating (PT)
Release
Release period
Repressor (IT)
Resident prophage (IT)
Residual fraction (MT)
Resistance to lysis from without
Restriction
Restrictive host (IT) (PT)
Restrictive infection (IT)
Restrictive infection (narrow definition)
Reversible adsorption
Rise
Rise period
S
Saturation (MT)
Secondary adsorption (MT)
Secondary infection (IT) (MT)
Secondary phage
Secondary virus
Single infection (MT)
Single burst experiment
Single step growth
Siphoviridae (MPD)
Site-specific recombination
Soft agar overlay (PT)
Specialized transduction
Spotting (PT)
Superinfection (IT) (MT)
Superinfection exclusion
Superinfection immunity (IT)
T
T phages
T-even phages
T-odd phages
Tail (MPD)
Tail fiber
Tail tip assembly
Tailed phage
Tailless phage
Tailocin
Tapemeasure protein (MPD)
Target bacteria (MT)
Temperate phage (MPD) (IT)
Temporal program
Titer (MT) (PT)
Total phage yield
Total virion count
Transduction
Translocation
Twort (1915)
Twort-d’Hérelle phenomenon
U–W
Uptake
Vegetative phage
Viral coat protein
Virion
Virion-like phage population growth (G)
Virion morphology
Virion morphogenesis
Virion progeny
Virulence
Virulent mutant (IT)
Virulent phage (IT)
Virus particle (MT)
Wavefront (PT)
Whole phages

Order of Addition (Reverse Chronological)

Terms as added to the original glossary at archaealviruses.org/terms/, 2011–2012. Date format YYMMDD.

(128) Infected bacteria 120807
(127) Adsorption rate 120807
(126) Wavefront 120807
(125) Soft agar overlay 120807
(124) Restrictive host 120807
(123) Relative efficiency of plating 120807
(122) Reaction-diffusion 120807
(121) Preadsorption 120807
(120) Plaque yield 120807
(119) Plaque productivity 120807
(118) Plaque morphology 120807
(117) Plaque halo 120807
(116) Infectious center 120807
(115) Plaque fecundity 120719
(114) Plaque count 120719
(113) Phage population growth 120719
(112) Parental infection 120718
(111) Mixed-indicator method 120718
(110) Microcolony 120718
(109) Lysis inhibition 120718
(108) Adsorption efficiency 120718
(107) Adsorption affinity 120718
(106) Polyphage 120718
(105) Monophage 120718
(104) Phage typing 120705
(103) Antirestriction 120705
(102) Bred phage 120705
(101) Phage population 120705
(100) Phage particle 120705
(99) Phage history 120705
(98) Repressor 120705
(97) Diffusion 120703
(96) Adsorption cofactor 120703
(95) Adsorption constant 120703
(94) Capacity 120703
(93) Adsorption resistance 120703
(92) Killing the winner 120703
(91) Phage receptor 120703
(90) Immediately productive 120703
(89) Lytic-lysogeny decision 120703
(88) Lambdoid phages 120703
(87) Lateral tail fiber 120703
(86) Immunity region 120703
(85) Immunity group 120703
(84) Insertion 120703
(83) Induction 120628
(82) Tailocin 120628
(81) Lysogenization 120628
(80) Lysogen 120628
(79) Lysogenic phage 120628
(78) Lysogenic infection 120628
(77) Lysogenic cycle 120628
(76) Destructive infection 120628
(75) Confluent lysis 120628
(74) Reduced infection vigor 120628
(73) Direct-plating plaquing method 120628
(72) Productive infection 120628
(71) Adolescent period 110727
(70) Phage typing 110727
(69) Lateral tail fiber 110726
(68) Phage particle 110726
(67) Tailocin 110726
(66) Single infection 110706
(65) Vegetative phage 110706
(64) Virulent phage 110706
(63) Burst 110704
(62) Liberation 110704
(61) Virion 110630
(60) Transduction 110630
(59) Titer 110630
(58) Temperate phage 110630
(57) Tailed phage 110630
(56) Superinfection 110630
(55) Spotting 110630
(54) Single step growth 110630
(53) Secondary adsorption 110629
(52) Rise 110629
(51) Prophage 110629
(50) Plaque-forming unit 110629
(49) Plaque 110629
(48) Phage therapy 110629
(47) Phage receptor 110629
(46) Multiplicity of infection 110629
(45) Lytic cycle 110629
(44) Lysogenic phage 110XXX
(43) Lysogenic cycle 110629
(42) Lysogen 110629
(41) Lysis from without 110629
(40) Lysis from within 110629
(39) Lysin 110629
(38) Lysate 110629
(37) Lawn 110629
(36) Latent period 110629
(35) Killing titer 110629
(34) Killing the winner 110629
(33) Irreversible adsorption 110629
(32) Insertion 110629
(31) Infective center 110629
(30) Infection 110629
(29) Induction 110628
(28) Residual fraction 110627
(27) Indicator bacteria 110627
(26) Immunity 110627
(25) Host range 110627
(24) Holin 110626
(23) Ghost 110626
(22) Free phage 110626
(21) Filamentous phage 110626
(20) Encounter 110626
(19) Efficiency of plating 110608
(18) Efficiency of center of infection (ECOI) 110607
(17) Eclipse 110607
(16) Depressor effect 110607
(15) CRISPR 110606
(14) Coinfection 110605
(13) Chronic infection 110605
(12) Capsid 110605
(11) Capacity 110530
(10) Bred phage 110530
(9) Bacteriophage-insensitive mutants (BIMs) 110529
(8) Attachment site 110529
(7) Attachment 110529
(6) Antirestriction 110529
(5) Adsorption (rate) constant 110529
(4) Adsorption cofactor 110529
(3) Adsorption 110529
(2) Active treatment 110529
(1) Abortive infection (Abi) 110529
(0) Burst size 110527

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Glossary of Bacteriophage Terms — phage.org/terms/phage.org — Stephen T. Abedon — Version 2026.05.14