Abbott-Smith Manual Greek Lexicon
ἅπτω (G681)
39 ἅπτω , [in LXX chiefly for נגע ;] prop., to fasten to ; hence, of fire, to kindle , light : Lk 8:16 11:33 15:8 , Ac 28:2 . Mid., c. gen., to fasten oneself to , cling to , lay hold of (so in π. ; MM, s.v.): Mt 8:3 , 15 , Jo 20:17 , al.; of carnal intercourse, I Co 7:1 ; with reference to levitical and ceremonial prohibitions, II Co 6:17 , Col 2:21 ; of hostile action, I Jo 5:18 (cf. ἀν- , καθ- , περι- άπτω ). SYN. : θιγγάνω , ψηλαφάω . ἅ. is the stronger, θ. , to touch , the lighter term. ψ. is to feel , as in search of something (Tr., Syn. , § xvii; Lft., Col. , 201 f.).
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain