There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
ilta-
verb. to stick in, prod, prick
ilt-
verb. to yoke, join
A verb appearing as G. ilt- “to yoke, join” in the Gnomish Lexicon of the 1910s (GL/50), likely based on the early root ᴱ√YḶTḶ (QL/106).
Neo-Sindarin: For purposes of Neo-Eldarin I adapt this early root as ᴺ√YALTA “yoke”, so I would adapt the Gnomish verb as ᴺS. ialtha- “to yoke”. For “to join” I would use ᴺS. ianna-.
ilt(h)a-
verb. to yoke, join
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
A verb in the Gnomish Lexicon of the 1910s glossed “to stick in, prod, prick”, likely based on the early root ᴱ√ᴵLTᴵL “thrust in” (GL/51; QL/42). Tolkien specified that the person or thing pricked was in the dative: G. on iltathi nin pieg “✱he stuck in to me (dative) a pin”.
Conceptual Development: Elsewhere in the document, Tolkien had G. elta- “to thrust, dig, poke (inward)” perhaps based on ᴱ√ELE “drive, push, thrust, send forth” (GL/32; QL/35). This was revised to elta-, eltha- “draw, tug, lug”, and finally G. eltha- “to alter, change”.