word-forming element meaning "down, downward," but also "through, on, against, concerning," etc., from Latinized form of Greek kata-, before vowels kat-, from kata "down, downward, down from, down to," from PIE *kmt- "down, with, along" (source also of Hittite kattan (adv.) "below, underneath," katta "along with"). Occasionally in Greek it had senses of "against" (catapult) or "wrongly" (catachresis), also "along, through, over, across, concerning." Also sometimes used as an intensive or with a sense of completion of action (catalogue). Very active in ancient Greek, this prefix is found in English mostly in words borrowed through Latin after c. 1500.
active word-forming element in English and in many verbs inherited from French and Latin, from Latin de "down, down from, from, off; concerning" (see de), also used as a prefix in Latin, usually meaning "down, off, away, from among, down from," but also "down to the bottom, totally" hence "completely" (intensive or completive), which is its sense in many English words.
As a Latin prefix it also had the function of undoing or reversing a verb's action, and hence it came to be used as a pure privative — "not, do the opposite of, undo" — which is its primary function as a living prefix in English, as in defrost (1895), defuse (1943), de-escalate (1964), etc. In some cases, a reduced form of dis-.
first element in many Celtic place names, meaning "cell (of a hermit); church; burial place," from Gaelic and Irish -cil, from cill, gradational variant of ceall "cell, church, burial place," from Latin cella (see cell).
word-forming element meaning "deputy, assistant, substitute," also "instead of, in place of," 15c., from Latin vice "in place of," ablative of vicis "a change, a turn, interchange alternation" (from PIE root *weik- (2) "to bend, to wind"). In Middle English sometimes borrowed in Old French form vis-, vi-.
word-forming element meaning "of or pertaining to India" (and some other place), from Greek Indo-, from Indos "India" (see India).
a Brythonic (Celtic) word for "head;" common in place names in Cornwall and Wales (such as Penzance; see also pendragon and Pennsylvania).
word-forming element meaning "on the near side of, on this side," from Latin preposition cis "on this side" (in reference to place or time), related to citra (adv.) "on this side," from PIE *ki-s, suffixed form of root *ko-, the stem of demonstrative pronoun meaning "this." Opposed to trans- or ultra-. Originally only of place, sometimes 19c. of time; 21c. of life situations (such as cis-gender, which is attested by 2011).
word-forming element meaning "toward; against; before; near; across; down," also used as an intensive, from Latin ob (prep.) "in the direction of, in front of, before; toward, to, at, upon, about; in the way of; with regard to, because of," from PIE root *epi, also *opi "near, against" (see epi-).
word-forming element meaning "killer," from French -cide, from Latin -cida "cutter, killer, slayer," from -cidere, combining form of caedere "to strike down, chop, beat, hew, fell, slay," from Proto-Italic *kaid-o-, from PIE root *kae-id- "to strike." For Latin vowel change, see acquisition. The element also can represent "killing," from French -cide, from Latin -cidium "a cutting, a killing."
before vowels seism-, word-forming element meaning "earthquake," from Greek seismos "a shaking, shock; an earthquake," also "an extortion" (compare colloquial shake (someone) down), from seiein "to shake, agitate, sway; to quake, shiver" from PIE root *twei- "to agitate, shake, toss; excite; sparkle" (source also of Sanskrit tvesati "to excite; to be excited, inflame, sparkle" and words in Avestan for "fears" and "fright, danger").