In rought drafts of notes on Eldarin Hands, Fingers and Numerals from 1968, Tolkien coined various words for “middle finger” using initial element √ENED “middle”: Q. enestil, enelde or enelde, the first of these in combination with Q. til “tip” with the usual sound change of d+t > t+t > st (VT47/26). But Tolkien soon revised the form to lepende, a combination of ✶lepe “finger” and Q. endë “middle” (VT47/27).
The word lepende “middle finger” reappeared in the polished version of these notes, along with a variant lepenel (VT47/10). Tolkien said this variant was an older word interpreted as “finger number-three”, but was originally based on Q. enel “in the middle, between” (VT47/11), with d/l variation in the primitive root √ENED (VT47/29 note #43). In yet another version of these notes, lepenel was the only word for “middle finger” (VT48/5).
Neo-Quenya: For purposes of Neo-Quenya, I’d use lependë as the usual word for “middle finger”, with †lepenel as an archaic variant.
[lependë] noun "middle finger", also lepenel (VT47:10, VT48:15; struck out)