"Hemiteleia" isn't in the OED or any other authority I can find in English - except for Philip Howard's "A Word in Your Ear" (1983), where he applies it specifically to rhyming slang. That seems to be where Bill Bryson and Wikipedia found it.

You mean the Greeks had a special name for a secondary feature of Cockney rhyming slang?

Give me a break.

Presumably Howard discovered it in a Greek rhetoric, but if so it must mean something a little different in Greek. It looks to me as though it means "half completion," but personally I have even less Greek than Latin.

At any rate, the more familiar "ellipsis" would seem to be sufficient, unless you want to sound one up on the OED.