LSJ
ωτος, Th. 4.80, etc., and Εἱλώτης, ου, ὁ, Hdt. 6.58, etc. ; fem. Εἱλωτίς, ίδος, ἡ, Plu. Ages. 3; — Helot, name of the Spartan serfs, derived by Hellanic. 188 J., Theopomp.Hist. 14, etc., from Ἕλος, a town of Laconia, whose inhabitants were enslaved; by others from Pass. of *ἕλω, = αἱρέω, cf. EM 332.53.
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)