cataclasm n.

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.

Old English holt "woods, forest, grove, thicket," common in place names, from Proto-Germanic *hultam- (source also of Old Frisian, Old Norse, Middle Dutch holt, Dutch hout, German Holz "a wood, wood as timber"), from PIE *kldo- (source also of Old Church Slavonic klada "beam, timber;" Russian koloda, Lithuanian kalada "block of wood, log;" Greek klados "twig;" Old Irish caill "wood"), from root *kel- "to strike, cut."