a prefix meaning “down,” “against,” “back,” occurring originally in loanwords from Greek (cataclysm; catalog; catalepsy); on this model, used in the formation of other compound words (catagenesis; cataphyll).
Also especially before a vowel, cat-;cath-, kata-.
Origin of cata-
< Greekkata-, combining form of katá down, through, against, according to, towards, during
word-forming element from Latinized form of Greek kata-, before vowels kat-, from kata "down from, down to." Its principal sense is "down," but occasionally it has senses of "against" (catapult)or "wrongly" (catachresis). 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.