An element in Morinehtar “Darkness-slayer”, a name of one of the Blue Wizards (PM/384). It seems to be an agental form of nahta- “to slay”, but the reason why the vowel is e is unclear.
Quenya
nehtar
slayer
nehtar
noun. slayer
nehta-
to slay
#nehta- (2) vb. "to slay" if such a stem can be isolated from #nehtar (see below). The (variant?) form nahta- is given in VT49:24.
nahta-
slay
nahta- (1) verb "slay" (nahtan "I slay"). Possible variant #nehta- see #nehtar. Passive participle nahtana in the phrase nahtana ló Túrin *"slain by Turin". (VT49:24)
nahta-
verb. slay
#nehtar noun "slayer", isolated from Morinehtar "Darkness-slayer" (PM:384, 385). It may be that a verbal stem #nehta- "to slay, kill" can also be isolated from this noun, though the attested form is actually nahta- (a possible example of A/E variation).