foci: meaning, definition, pronunciation and examples
C1Formal, Academic, Technical
Quick answer
What does “foci” mean?
The plural form of 'focus', meaning the central points of attention, activity, or interest.
Audio
Pronunciation
Definition
Meaning and Definition
The plural form of 'focus', meaning the central points of attention, activity, or interest; in mathematics and science, specific points related to curves, lenses, or ellipses.
Can refer to multiple centers of energy, infection, or development; in optics, the points where light rays converge; in geometry, the fixed points used to define conic sections.
Dialectal Variation
British vs American Usage
Differences
No significant difference in meaning or usage. Both varieties accept 'foci' as the plural, with 'focuses' being a more common alternative in everyday language.
Connotations
In both varieties, 'foci' carries a formal, precise, and often technical connotation.
Frequency
Equally low-frequency in both UK and US English, reserved for specialized contexts.
Grammar
How to Use “foci” in a Sentence
The foci of [noun phrase] were...[Noun phrase] has/have multiple foci.to identify the foci of [noun phrase]Vocabulary
Collocations
Examples
Examples of “foci” in a Sentence
verb
British English
- The committee's efforts are currently focussed on several key initiatives.
American English
- The committee's efforts are currently focused on several key initiatives.
adverb
British English
- [No direct adverbial form from 'foci'. From 'focus': 'He listened focussedly.']
American English
- [No direct adverbial form from 'foci'. From 'focus': 'He listened focusedly.']
adjective
British English
- The focussed beam of light was intense.
- She has a very focussed approach to her work.
American English
- The focused beam of light was intense.
- She has a very focused approach to her work.
Usage
Meaning in Context
Business
Rare. Might be used in formal strategy documents: 'Our strategic foci for the next quarter are digital transformation and sustainability.'
Academic
Common in research papers across sciences, mathematics, and social sciences: 'The study identified three main foci of cultural change.'
Everyday
Extremely rare. The singular 'focus' or plural 'focuses' would be used.
Technical
Standard in optics, geometry, geology, and medicine: 'The ellipse is defined by its two foci.' 'The MRI revealed several small foci of inflammation.'
Watch out
Common Mistakes When Using “foci”
- Using 'foci' in casual conversation instead of 'focuses'.
- Mispronouncing it as /ˈfɒk.i/ (like 'foxy').
- Treating it as a singular noun (e.g., 'a foci').
FAQ
Frequently Asked Questions
Both are correct. 'Foci' (pronounced /ˈfəʊ.saɪ/ or /ˈfoʊ.saɪ/) is the traditional Latin plural and is preferred in formal, scientific, and academic writing. 'Focuses' is more common in general English.
In British English, it's /ˈfəʊ.saɪ/ (FOH-sigh). In American English, it's /ˈfoʊ.saɪ/ (FOH-sigh). The first syllable rhymes with 'go', and the second sounds like the word 'sigh'.
It is not recommended, as it sounds very formal and technical. In everyday speech, use 'focuses' or rephrase using 'centers', 'main points', or 'key areas'.
The most common mistake is using 'foci' as if it were singular (e.g., 'a foci'). Remember, 'focus' is singular, 'foci' (or 'focuses') is plural. Another mistake is mispronunciation, such as saying /ˈfɒk.i/.
The plural form of 'focus', meaning the central points of attention, activity, or interest.
Foci is usually formal, academic, technical in register.
Phrases
Idioms & Phrases
- “[No common idioms use 'foci'. The singular 'focus' is used in idioms like 'in focus', 'out of focus', 'focus group'.]”
Learning
Memory Aids
Mnemonic
Think 'FO-CI' sounds like 'FOe-SIGH'. A mathematician might sigh, 'Oh no, I have to calculate both foes (foci) of this ellipse!'
Conceptual Metaphor
CENTERS ARE POINTS (OF CONVERGENCE/ATTENTION)
Practice
Quiz
In which context is the word 'foci' MOST appropriately used?