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.
stak
root. split, insert
stakta-
verb. to split
nestak-
verb. to insert, stick in
sahta-
verb. to split
A verb appearing as ᴱQ. sahta- “to split” in Early Qenya Phonology of the 1920s derived from primitive ᴱ✶stak+ta- (PE14/66).
Neo-Quenya: Since the root ᴹ√STAK “split, insert” survives in Tolkien’s later writings, I think ᴺQ. sahta- “to split” can be retained for purposes of Neo-Quenya. It does conflicted with the later verb Q. sahta- “induce” from the 1950s, but I think the two can coexist.
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.
nestag-
verb. to insert, stick in
A verb in The Etymologies of the 1930s appearing in its Noldorin-style infinitive form nestegi “insert, stick in”, derived from ON. nestak- under the root ᴹ√STAK “split, insert” (Ety/STAK). As such, its unmutated stem would be ✱nestag-. Its initial prefix ne- is derived from ᴹ✶ndē̆- “in, inside” under the (deleted) root ᴹ√NĒ̆ (EtyAC/NĒ̆).
thag-
verb. to split
A neologism for “to split” coined by Gilruin on 2025-08-20 in the Vinyë Lambengolmor Discord Server (VLDS), derived from ᴹ√STAK of similar meaning. It replaced another of his neologisms thaetha-, which is problematic since one of the th should dissimilate from the other.
thaetha-
verb. to split
thanc
split
(adj.) thanc (forked, cleft), pl. thainc
thanc
split
(forked, cleft), pl. thainc
mitta-
verb. to insert, to insert; [ᴹQ.] to come in, [ᴱQ.] enter (intr.)
A verb glossed “insert” in notes from the 1950s derived from the root √MI “in” (VT43/30). ᴹQ. mitta- was also glossed “insert” in the Quenya Verbal System (QVS) from 1948 (PE22/110), but in some sentences in the same document it was translated “come in” used intransitively: ᴹQ. á he mittar “let them come in” and mitt’ā́ “come in!” (PE22/106). It was used to mean “get in” in a phrase from Demonstrative, Relative, and Correlative Stems (DRC), also from 1948, in the phrase: me·mittanelme i·mbarenna “we got into the house” (PE23/97), with the thing entered in the allative and a reflexive pronoun -lme “us” as the object. In its early appearance in the Qenya Lexicon of the 1910s, ᴱQ. mitta- was glossed “enter (intr.)” and derived from the early root ᴱ√MĪ (QL/61).
Neo-Quenya: For purposes of Neo-Quenya, I would assume mitta- can be used intransitively for “enter [= insert oneself]” and transitively for “insert”, with the thing inserted as the direct object and the thing entered in the allative. Hence mittanen latil i fendenna “I inserted a key into the door” but mittanen i fendenna “I entered [inserted myself] into the door”. With no object or allative, it simply means “go/come in”.
sahta-
verb. to split
A root in The Etymologies of the 1930s glossed “split, insert” with derivatives like ᴹQ. sanka/N. thanc “cleft, split” and N. nestegi “insert, stick in” (Ety/STAK). S. thanc remained an element in S. Orthanc “Forked Height” (LotR/555; UT/400), indicating the ongoing validity of this root.