2 syllables: Fo, ci. Stress on Fo.
FOH-seye
/ˈfoʊ.saɪ/
Foci is pronounced FOH-seye (/ˈfoʊ.saɪ/). It has two syllables (Fo-ci), with the stress on "Fo". Foci is the plural of focus, referring to multiple centers of interest, attention, or activity, or to multiple focal points in geometry or optics. In biology or sociology, it can describe central points of study or activity. The term is used across disciplines and often requires careful pronunciation to avoid confusion with singular “focus.”.
nounFoci is the plural of focus, referring to multiple centers of interest, attention, or activity, or to multiple focal points in geometry or optics. In biology or sociology, it can describe central points of study or activity. The term is used across disciplines and often requires careful pronunciation to avoid confusion with singular “focus.”
"The researcher mapped the foci of the disease outbreak to identify transmission hubs."
"Her interests span several foci, including climate science and public health."
"In optics, the foci of the lenses determine where the image forms."
Pronounced /ˈfoʊ.saɪ/ in US and UK English, with primary stress on the first syllable. The second syllable rhymes with ‘eye.’ Mouth position: start with a closed syllable /ˈfoʊ/ as in ‘foe,’ then glide to /saɪ/ with a high front closing diphthong. For many learners, think ‘FOH-sigh.’ Audio reference: listen for the long O in the first syllable and the /aɪ/ in the second.
Common errors: 1) Pronouncing the second syllable as /si/ rather than /saɪ/ due to confusion with ‘focus’ vs ‘foci’; fix by using /saɪ/ as in ‘sigh.’ 2) Under- or over-stressing the first syllable, producing FO-si or fo-SI; keep primary stress on FOH. 3) Dropping the final vowel to /ɪ/ or /i/; retain the /aɪ/ glide. Practice with minimal pairs like ‘foe-sigh’ vs ‘foe-see’ to reinforce the /aɪ/ vowel.
Across accents, /ˈfoʊ.saɪ/ is fairly stable. In US and UK, the /foʊ/ and /aɪ/ vowels remain, with non-rhotic UK accents still keeping the syllable break; rhoticity does not change the pronunciation of /ˈfoʊ/. Australian English mirrors US/UK diphthongs but with subtle vowel height differences: /ˈfoʊ.saɪ/ remains, but the /oʊ/ can be closer to /əʊ/ for some speakers. Accent variation is mainly about vowel quality rather than stress.
Difficulty stems from the two-syllable structure with a diphthong in the first syllable and a rising diphthong in the second. Learners struggle with keeping the /oʊ/ clearly rounded before moving to /aɪ/; it’s easy to mis-sing the middle transition. Also, plural-specific pronunciation differs from the singular 'focus,' so speakers must maintain the final /aɪ/ rather than an /i/ or /ɪ/ sound.
A key focal point is the glide from /oʊ/ to /aɪ/, which creates a distinctive two-part vowel in rapid speech. Ensure the second syllable begins with a clear onset /s/ followed by /aɪ/ without a separate vowel. This makes 'foci' sound precise rather than like a clipped /ˈfo-si/ or /ˈfoʊ.si/. Paying attention to the diphthong boundary can dramatically improve naturalness.
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Foci comes from the Latin plural of focus, which originally meant a hearth or fireplace, extending to the center or point of convergence in various contexts. The word entered English via scientific and mathematical usage, especially in geometry and optics, where “focus” denotes a point where rays converge. The Latin root focuses on the idea of a center or central point, derived from the Proto-Italic *focus* and ultimately from the PIE root *bhā-/*bhos-* meaning ‘to burn’ or ‘to shine,’ reflecting the hearth and focal light concept. In English, the plural form foci has been established since the 19th century, driven by mathematical terminology and later adopted more broadly in biology, linguistics, and information science. The singular focus is often used in everyday language, while foci retains a more formal, disciplinary nuance, particularly in academic writing and technical discourse. The word’s pronunciation and pluralization are well-established, with foci pronounced /ˈfoʊ.saɪ/ in standard usage and historically variably as /ˈfoʊ.si/ in some dialects; modern usage favors the long “o” in the first syllable and a high front vowel in the second syllable, with stress on the first syllable. First known attestations in English date to the 17th–18th centuries within mathematical texts and increasingly in natural sciences by the 19th century.
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Words that rhyme with "Foci"
-oci sounds
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