Quick Definition
I appear, am seen
Strong's Definition
to gaze (i.e. with wide-open eyes, as at something remarkable; and thus differing from G991 (βλέπω), which denotes simply voluntary observation; and from G1492 (εἴδω), which expresses merely mechanical, passive or casual vision; while G2300 (θεάομαι), and still more emphatically its intensive G2334 (θεωρέω), signifies an earnest but more continued inspection; and G4648 (σκοπέω) a watching from a distance)
Derivation: a (middle voice) prolonged form of the primary (middle voice) ; which is used for it in certain tenses; and both as alternate of G3708 (ὁράω);
KJV Usage: appear, look, see, shew self
Thayer's Greek Lexicon
ὀπτάνω (ὈΠΤΩ): to look at, behold; middle present participle ὀπτανόμενος; to allow oneself to be seen, to appear: τίνι, Act_1:3. (1Ki_8:8; Tob_12:19; (Graecus Venetus, Exo_34:24).)
Mounce Concise Greek Dictionary
ὀπτάνομαι optanomai 1x
to be seen, appear, Act_1:3
Abbott-Smith Greek Lexicon
† ὀπτάνω ,
[in LXX : 1Ki_8:8 ( H7200 ni .), Tob_12:19 * ;]
late present as from ὤφθην ( = ὁράω ); mid ., ὀπτάνομαι , to allow oneself to be seen, to appear. c . dat ., Act_1:3 . (For exx . from Papyri, v. Deiss., LAE , 79, 252 6; MM , ii, xviii.) †
Moulton & Milligan — Vocabulary of the Greek NT
ὀπτάνομαι [page 454]
ὀπτάνομαι can be definitely removed from the list or so-called Biblical words (Grimm-Thayer, p. 695), since to its occurrences in the LXX (3 Ki. 8:8 [MT 2Ki_8:8 ], Tob_12:19 : cf. P Oxy XIII. p. 4) and the NT ( Act_1:3 ), we can add such early exx. as P Par 49 .33 (B.C. 164 158) (= Witkowski, 2 p. 72) εἰ δὲ δι᾽ ἄλλο τι οὐκ ὀπτάνεταί μοι , P Tebt I. 24 .5 (B.C. 117) καὶ μηδαμῶς ὀπτανομένων ὑπ̣[ . . . Of a later date we have the great magical papyrus P Par 574 .3033 ( c. A.D. 300) ὁρκίζω σε τὸν ὀπτανθέντα τῷ Ὀ (= Ἰ )σραὴλ ἐν στύλῳ φωτινῷ καὶ νεφέλῃ ἡμερινῇ , an interesting reference to Exo_13:21 (see Deissmann LAE p. 252). On the implications involved in the use of ὀπτάνομαι in Act_1:3 as denoting actual appearance as distinguished from vision cf. Knowling EGT ad l.
STEPBible — Tyndale Abridged Greek Lexicon
ὀπτάνω
[in LXX: 3Ki.8:8 (רָאָה ni.), Tob.12:19 * ;]
late present as from ὤφθην (= ὁράω); mid., ὀπτάνομαι, to allow oneself to be seen, to appear. with dative, Act.1:3. (For exx. from π., see Deiss., LAE, 79, 2526; MM, ii, xviii.) †
(AS)