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The words "quadcopter" and "novocaine" have unusual etymologies. "Quadcopter" comes from a combination of quad for "four" and copter from "helicopter," and "novocaine" comes from novo for "new" and caine from "cocaine."
What's odd here is that both "copter" and "caine" break apart the original words at a spot that isn't the natural split in their own etymologies. "Helicopter" comes from helico and pter, and "cocaine" comes from coca and ine. The splits of "copter" and "caine" make a ton of sense given that they're at syllable boundaries and the new words don't seem at all unusual.
Is there a term for new words like quadcopter and novocaine whose origin involves cleaving an existing word at a spot that doesn't match their etymologically?