The headword is the perfect middle-passive participle, genitive plural, of the verb tele/w (I develop, accomplish, execute, perform); see generally LSJ s.v. The earliest attestation of the headword form is Aristotle, Generation of Animals 779a25, where he notes that "the newborn [sc. human] is asleep more than any other animal, for it is born less developed than any other of the having been fully developed" animal infants. (The contrast here would be with e.g. a dog, whose puppies are born blind, and so not with fully developed organs; see Peck, pp. 492-3n.) However, given the gloss (see next note), the entry is thought to be generated by the instance of the headword form at Hosea 4.14 LXX: "I will not punish your daughters whenever they turn to prostitution, nor your wives whenever they commit adultery; for the men themselves consort among prostitutes and sacrifice among those [e.g. temple prostitutes] that have been consecrated."
[1] The gloss is the same form as the headword, but from the verb miai/nw, I stain, sully, taint, defile; see generally LSJ s.v.