πειθήνιος
From LSJ
τὸ δ' ἐξαίφνης τὸ ἐν ἀναισθήτῳ χρόνῳ διὰ μικρότητα ἐκστάν → suddenly refers to what has departed from its former condition in a time imperceptible because of its smallness
English (LSJ)
Dor.πειθ-άνιος [ᾱ], ον, (ἡνία)
A obedient to the rein, of a horse, Plu.Lyc.30 : metaph., Id.2.592c: generally, obedient, γυνή M.Ant. 1.17, Hymn.Is. 101, cf. Plu.2.90b ; στράτευμα well-disciplined, Onos. 10.9 ; ψυχή Hierocl. in CA16p.456M. ; τὸ π. submissiveness, docility, Plu.2.442c. Adv. -ίως ib.102e, Ph.1.184; in Surgery, gently, Herod. Med. ap. Orib.10.18.15, Sor.1.70b, 2.10. II Act., that makes obedient, χαλινοί Plu.2.369c ; λόγος Vett. Val.150.28.