DAESH is the acronym for the actual Arabic name that they use. Translate the actual name into English it becomes "Islamic State of Iraq and ash-Sham." Depending on how you translate ash-Sham you either get Syria or the Levant, hence ISIS or ISIL.

In Arabic it's a word in its own right (rather than an acronym) meaning 'a group of bigots who impose their will on others' That it can be 'differently conjugated' to mean either the phrase above or 'to trample and crush' That one of the words in the acronym also means 'to trample or crush'