Written onen in some editions of LotR. In the Qenyaqetsa, Qenya anta- is marked as having an irregular past tense áne. Assuming the same sound-shifts as observed in other words, this would indeed lead to onen in Sindarin, see PE/12:31 and TT/14:48-49
Sindarin
ónen
suffix. I gave
ónen
noun. I gave
anna-
verb. to give, †add to
The most commonly accepted Sindarin verb for “give” is S. anna-, but Tolkien experimented with a variety of other forms throughout his life. Its best known form is its strong past ôn “gave” as in ónen i-Estel Edain “I gave Hope to the Dúnedain” from The Lord of the Rings Appendix A (LotR/1061).
Conceptual Development: The Gnomish Lexicon of the 1910s had G. antha- “give” (GL/19), equivalent to ᴱQ. anta- under the early root ᴱ√ANA “give, send towards” in the contemporaneous Qenya Lexicon (QL/31). In the 1910s the medial combination nth survived, but by the 1930s medial nth became nn, and The Etymologies of the 1930s had N. anno “to give” under the root ᴹ√ANA “to, towards” as the equivalent of ᴹQ. anta- “give” (Ety/ANA¹). The Sindarin version of the Lord’s Prayer from the mid-1950s had imperative anno “give” in anno ammen sír i mbas ilaurui vín “give us this day our daily bread” (VT44/21).
Quenya Notes (QN) from 1957 instead had S. anta- “give” (PE17/147), which seems to belong to a (brief?) period where Tolkien abandoned the development of nt to nn; see my essay on Sindarin Articles and Mutations from Parma Eldalamberon #23 for further discussion. There was a verb form anha- “give” from around 1967 which might represent a conceptual stage where nt became voiceless nh but did not further advance to voiced nn (PE17/147). In Late Notes on Verb Structure (LVS) from 1969, Tolkien the described verb’s derivation as follows:
> The Q. causative anta ... is due to blending AN with the unrelated verbal stem {ƷAN >>} HAN “give”, {which in Q. and S. lost the initial spirant ʒ, that in T. became h- >>} which in S. lost the initial breath h of CE, that in Q., T. remained h- (T hanin “I give”) ... S[indarin] strong verb (lost in Q.) aned, pa.t. ónen, T hanna (PE22/163 and note #99).
This last example implies a basic/strong verb form S. an- “give” [e.g. ✱ân “he gives”, ✱enin “I give”] with gerund aned “✱giving” and strong past ôn “✱gave”. It is possible, though, that only the past and gerund were strong, and the base verb remained S. anna- analogous to T. hanna.
Neo-Sindarin: For purpose of Neo-Sindarin I would stick with S. anna- “give”, since it is a direct equivalent of the well-attested Q. anta- “give” if one assumes nt > nth > nn, which seems to be the rule for most of the 1930s through 1960s.
im
i
but as subject usually simply the ending -n, as in ónen ”
Lossoth
noun. the Snowmen
anfangrim
noun. the Longbeards (a tribe of Dwarves)
anglennatha
verb. (he) will approach
anha-
verb. to give
avo
verb. don't!
Used as a negative adverb before an imperative: avo garo "don't do it!". Sometimes used as prefix: avgaro
avon
verb. I won't
cuio
verb. live!
dagorath
noun. all the battles
drúwaith
noun. the wilderness of the Drû-men (q.v.)
falathrim
noun. people of the Falas
galadhad
noun. the Two Trees of Valinor
im
pronoun. I
In late writings (see esp. VT/47:37-38), Tolkien reinterpreted this form as a reflexive pronoun (= "self").
lammas
noun. account of tongues
lâf
verb. (he) licks
lôd
verb. (he) floats
noro
verb. run! ride!
Untranslated in LotR, but written nora-lim and rendered as "ride on" in RS/196 (not a literal translation) and later translated as "run swift" in RC/195. A verb nor- is attested in the old Gnomish lexicon, PE/11:61, with the meaning "to run, roll"
pêd
verb. (he) says
rammas
noun. (great) wall
rochirrim
noun. horse-lords, the people of Rohan
tôl
verb. (he) comes
According to WJ/301, the expression tôl acharn "vengeance comes" was later changed to tûl acharn by Tolkien
ón annin
*he gave (it) to me
ónen i-estel edain
I gave Hope to the Dúnedain
ni
pronoun. I
nin
i
”me”, genitive nín ”my”, dative anim or enni ”to me, for me”.
v. pa.t. & pron. suff. I gave. ónen i·Estel Edain 'I gave the "Hope" (to) Men'.