Noun
(geology, astronomy) A crater formed from a hypervelocity impact, typically of a meteorite, as opposed to one formed by other means such as vulcanism.
A crater formed by a process involving impact (not necessarily a hypervelocity one).
Source: en.wiktionary.orgImpact crater diameters seen range from 0.1 km a limit defined by the imaging resolution to over 100 km, not counting the multi-ring structures. Source: Internet