Crevice and crevasse are very similar words: they both derive from the Old French crever, a verb meaning "to break or burst," and both refer to an opening of some kind. In fact, you can say that the only notable distinction between the two is the size of the openings they denote. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.