Foci
/ˈfoʊ.saɪ/noun
Plural of focus; points where rays, lines, or forces converge, or centers of activity or attention.
Did you know?Latin focus originally meant a hearth or fireplace, and only later did it expand into the scientific idea of a point where things meet, concentrate, or burn brightest.
Etymological Timeline
Proto-Indo-European
PIE
*dʰeh₁-
“to put, place, set”
Latin
Latin
focus
“hearth, fireplace, domestic fire”
Late Latin
Latin
focus
“fireplace; center of activity”
Modern English
English
focus
“a central point of attention, activity, or convergence”
Modern English
English
foci
“plural of focus”