ἀκλῐνής · aklinēs — LSJ
bending to neither side, unswerving, Pl. Phd. 109a; πρὸς τὸ δίκαιον Nic.Dam. p.144D.; impartial, ἀκοαί POxy. 904.9 (V A.D.); regular, ἀκλινέων καλάμων AP 10.11 (Satyr.), etc.: Math., without inclination, of a perpendicular, Procl. in Euc. p.132F.; horizontal, of a plane, Papp. 1048.2, Hero Dioptr. 19: Music., fixed, of notes in scale, Alyp. 4: Medic., persistent, πυρετοί Herod. ap. Orib. 6.20.24. Adv. -νῶς Ph. 2.669; Ion. -νέως AP 5.54 (Diosc.).
metaph., steadfast, steady, φιλία ib. 12.158 (Mel.); ὁμολογία Ep.Hebr. 10.23; ψυχή Luc. Dem.Enc. 33; unmoved, tranquil, Nonn. D. 35.11, al.