Pronunciation: (krak'ing), [key]
(in the distillation of petroleum or the like) the process of breaking down certain hydrocarbons into simpler ones of lower boiling points by means of excess heat, distillation under pressure, etc., in order to give a greater yield of low-boiling products than could be obtained by simple distillation. Cf. catalytic cracking.
extremely; unusually: We saw a cracking good match at the stadium.
1. done with precision; smart: A cracking salute from the honor guard.
2. get cracking. See crack (def. 31).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.