The headword phrase quotes Sophocles, Electra 863 (web address 1): Electra expresses her grief, in the form of a question to the chorus, after the report of the death of her brother Orestes.
In her recitation, Electra uses the same adjective, tmhto/s, h/, -o/n (cut, shaped by cutting, here in the masculine (also neuter) dative plural; see LSJ s.v. and Ellendt s.v.), that the Paedagogus did in deceptively delivering the original story at Sophocles, Electra 747 (web address 2). It would seem to directly refer to manufacturing the straps by cutting them from a hide, yet the lemma's adjective appears in other accounts of chariot accidents, as at Euripides, Hippolytus 1245 (web address 3). Indeed, for i(ma/s (see LSJ s.v., rein), it functions as an epithet (Jebb, pp. 124-5): trim reins.
The noun in the lemma, o(lko/s (here in the masculine dative plural; see LSJ s.v.), also means winch and furrow, drawing an allusion to the impressions made by the straps in the hides of horses pulling the chariot car (Hogan, p. 296).
[1] This part of the entry follows the Sophoclean scholia.
[2] The Paedagogus' account is false, intended to deceive Clytemnestra and Electra; cf. omega 35.