infest
C1Formal, Neutral, Medical, Technical (in contexts of pest control, biology).
Definition
Meaning
(of pests, vermin, or anything unpleasant) to be present in large numbers, causing damage or nuisance; to overrun.
To be persistently or annoyingly present, often referring to abstract things like problems, fears, or unwanted thoughts.
Linguistics
Semantic Notes
The subject is typically the pest/problem, and the object is the place/person being affected. Implies a negative, harmful, and invasive presence.
Dialectal Variation
British vs American Usage
Differences
No significant difference in core meaning or usage. Spelling conventions (e.g., 'infested' past tense) are identical.
Connotations
Identical. Strongly negative, associated with disease, decay, or overwhelming nuisance.
Frequency
Similar frequency; slightly more common in technical or reportage contexts in both varieties.
Vocabulary
Collocations
Grammar
Valency Patterns
[pest] infest [place/person][place/person] be infested with/by [pest]abstract: [thought/fear] infest [mind]Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “[be] infested with rats/vermin”
- “a mind infested with doubts”
Usage
Context Usage
Business
Rare. 'The old warehouse was infested with pigeons, causing a health and safety issue.'
Academic
Common in biology/ecology. 'The lake became infested with an invasive species of algae.'
Everyday
Common for pests. 'Our summer house is infested with ants.'
Technical
Standard in pest control, medicine, agriculture. 'The patient's scalp was infested with head lice.'
Examples
By Part of Speech
verb
British English
- Mice often infest old barns.
- The garden was completely infested with slugs.
- Dark thoughts began to infest his mind.
American English
- Termites infested the foundation of the house.
- The apartment got infested with roaches.
- A sense of dread infested the community after the news.
adverb
British English
- N/A - No standard adverbial form. 'Infestingly' is non-standard.
American English
- N/A - No standard adverbial form.
adjective
British English
- The infested mattress had to be burned.
- They called pest control for the infested loft.
American English
- The infested crop was a total loss.
- They condemned the infested building.
Examples
By CEFR Level
- The old food attracted rats. They infested the basement.
- Our holiday cottage was infested with spiders, so we left early.
- Paranoia infested the political discourse, making rational debate impossible.
Learning
Memory Aids
Mnemonic
Think: 'INvasion of uninvited guESTs' → INFEST.
Conceptual Metaphor
NEGATIVE ENTITIES ARE INVADERS / DISEASE. Unwanted things are conceptualized as hostile organisms taking over a space.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not confuse with 'infect' (заражать). 'Infest' is about numbers/occupation (населять, кишеть), not disease transmission. Russian 'заражать' usually maps to 'infect'.
Common Mistakes
- Using 'infest' for a single pest (requires many). Confusing 'infest' (pests) with 'infect' (disease/germs). Using the wrong preposition (infest WITH, not BY, though 'by' is possible in passive).
Practice
Quiz
Which sentence uses 'infest' correctly?
FAQ
Frequently Asked Questions
'Infest' refers to being overrun by many pests/organisms (insects, rodents). 'Infect' refers to contamination by a disease-causing agent (virus, bacteria).
Yes, metaphorically. Weeds can infest a garden, and abstract concepts like doubts or corruption can infest a system or one's mind.
Yes, without exception. It describes an unwelcome, harmful presence.
In passive constructions, 'infested with' is most common (e.g., 'infested with lice'). 'Infested by' is also grammatically correct but less frequent.