A word for a (male) child in The Etymologies of the 1930s added to its entry when the meaning of the root ᴹ√SEL-D was changed from “daughter” to “child” (Ety/SEL-D). It was written above its feminine equivalent ᴹQ. selde and an apparently neuter form ᴹQ. selda was written to the right, making seldo likely the masculine form as suggested by Carl Hostetter and Patrick Wynne (EtyAC/SEL-D), hence = “✱boy”.
Qenya
il-
prefix. no, not
il(u)-
prefix. all the, the whole, the entire; all, any
nilmo
noun. friend
-el
suffix. friend
-ser
suffix. friend
aran
noun. child
elda
noun. Elf
helde
noun. friend
heldo
noun. friend
helmo
noun. friend
lá
adverb. no, not
málo
noun. friend
nande
noun. harp
ná-
verb. to be
qen
noun. Elf
qende
noun. Elf
seldo
noun. child, child [m.], *boy
sermo
noun. friend
seron
noun. friend
sondo
noun. friend
ye-
verb. to be
This word first appeared as ᴱQ. ar (arn-) “child” in the Qenya Lexicon of the 1910s (QL/32) and its stem form arn- appeared in the Poetic and Mythological Words of Eldarissa (PME/32). The word reappeared in Early Qenya Word-lists of the 1920s (PE16/135), but in the Early Noldorin Dictionary the Qenya form was given as arne. In the Declension of Nouns from the early 1930s, the word appeared as ᴹQ. aran (arn-) “child” (PE21/19), but there is no sign of it from this point forward, probably displaced by Q. aran “king”.