Probably strengthened from the base of histemi; properly, to set fast ("stall"), i.e. (figuratively) to repress (reflexively, abstain from associating with) -- avoid, withdraw self.
see GREEK histemi
1. to set, place, set in order, arrange; to fit out, to prepare, equip; middle present στέλλομαι, to prepare oneself, to fit out for oneself; to fit out for one's own use: στελλόμενοι τοῦτο μή τίς etc. arranging, providing for, this etc. i. e. taking care (A. V. avoiding), that no one etc. 2 Corinthians 8:20 (cf. Winers Grammar, § 45, 6 a.; Buttmann, 292 (252)).
2. to bring together, contract, shorten: τά ἱστία, Homer, Odyssey 3, 11; 16, 353; also in middle Iliad 1, 433; to diminish, check, cause to cease; passive, to cease to exist: βουλομένῃ τήν λύπην τοῦ ἀνδρός σταλῆναι, Josephus, Antiquities 5, 8, 3; ὁ χειμών ἐσταλη, ibid. 9, 10, 2; middle to remove oneself withdraw oneself to depart, followed by ἀπό with the genitive of the person, to abstain from familiar contact with one, 2 Thessalonians 3:6. (Compare: ἀποστέλλω, ἐξαποστέλλω, συναποστέλλω, διαστέλλω, ἐπιστέλλω, καταστέλλω, σὑν᾿στέλλω, ὑποστέλλω.)