The Quenya word for “finger” appearing in various notes on Eldarin Hands, Fingers and Numerals from 1968, derived from the root √LEP “pick up” (VT47/10; VT48/5).
Conceptual Development: The Quenya “finger” words went through quite a few conceptual changes, but they were always based on the root √LEP. The earliest of these was ᴱQ. let (lept-) “finger” in the Qenya Lexicon of the 1910s under the early root ᴱ√LEPE with plural form lepsi (QL/53). In Qenya word lists of the 1920s, however, this became ᴱQ. lepta “finger”, still with the plural lepsi (PE15/72; PE16/137).
The form was ᴹQ. let (leps-) in the Declension of Nouns of the early 1930s (PE21/19, 26), expanded to ᴹQ. lepse “finger” in The Etymologies written around 1937, based on the root ᴹ√LEPET of the same meaning (Ety/LEPET). This form demonstrated the 1930s sound change whereby pt became ps (PE19/44 note #44). Tolkien revised this sound change so that the result remained pt (PE19/44), and in 1940s drafts to The Lord of the Rings Tolkien used the word ᴹQ. rakkalepta “✱claw-fingered” in Treebeard’s description of orcs (SD/68), though in the published version this word only appeared in English.
In the Outline of Phonology from the 1950s (OP1) Tolkien considered restoring the sound change pt > ps (PE19/84 note #75), and Q. lepsë appeared in notes from the late 1950s or early 60s on the tree name S. lebethron, so named because “its leaves (like chestnut) [were] shaped like a fingered hand” (PE17/89). However, he again abandoned this, clarifying that the actual result of [[q|[pt] was a spirantal [ɸt]]] (spelled pt to represent the bilabial pronunciation), and that in Tarquesta pronunciation (Exhilic Quenya of the first age) the [ɸ] vocalized to [u̯] so that ✶lepta > leꝑta > Q. leu̯ta “finger” (PE19/84). Q. lepta appeared in several words in the 1960s: Q. leptafinya “clever-fingered” (PE17/17) and Q. Tyelpelepta “✱silver-fingered” (VT47/27).
In drafts of the 1968 notes on Eldarin Hands, Fingers and Numerals, lepta reappeared as an independent word, but with the gloss “thumb” (VT47/27). In the final versions of these notes, however, Tolkien used leper for “finger”, as noted above.
Neo-Quenya: For purposes of Neo-Quenya, I would use leper for “finger”, but would retain lepta as an adjective meaning “fingered”, especially in compounds like [ᴹQ.] raccalepta “claw-fingered”.
leper (pl. leperi given) noun "finger" (VT44:16, VT47:10, 14, 24, VT48:5; an older source gives the word for "finger" as lepsë, q.v.)