Lexical Definition

‎κρούω‎ kroúō (kroo'-o) to knock ^G:V
apparently a primary verb

knock.

• to rap

Abbott-Smith

κρούω, [in LXX: seq. ἐπί, Jg 19:22, Ca 5:2 (דִפק);] c, acc., τ. αὐλαίαν, Jth 14:14*;]
to strike, knock: at a door (κόπτειν, in Att.), Mt 7:7, 8, Lk 11:9, 10 12:36, Ac 12:16, Re 3:20; c. acc., τ. θύραν, Lk 13:25, Ac 12:13.†

Abbott-Smith References

Liddell-Scott-Jones

κρούω,

future -σω [Refs 5th c.BC+]: aorist [Refs 6th c.BC+]: perfect [Refs 5th c.BC+] —middle, aorist [Refs 5th c.BC+]:—passive, aorist [Refs 3rd c.BC+]: perfect κέκρουμαι (ἀπο-) [Refs 5th c.BC+]:—strike, smite, [Refs 5th c.BC+]; κρούσας δὲ πλευρὰ [τῶν ἵππων] [Refs 5th c.BC+]; also εἰς τὴν χεῖρα τοῖς δακτύλοις κ. with the fingers, [Refs 2nd c.AD+] tickles, [Refs 4th c.BC+]

__2 strike one against another, strike together, κ. χεῖρας clap the hands, [Refs 6th c.BC+] [same place]: metaphorically, ἀλλήλων τοὺς λόγους τοῖς λόγοις ἐκρούομεν ἄν would have knocked their heads together, [Refs 5th c.BC+]
__3 κ. πόδα (i.e. κ. τὴν γῆν τῷ ποδί), in dancing, [Refs 5th c.BC+] (Lyric poetry).
__4 metaphorically from tapping an earthen vessel, to try whether it rings sound (compare [Refs]: examine, try, prove, [Refs 6th c.BC+]; κἂν διαπειρώμενος κρούσῃς [τὸν κόλακα] [Refs 1st c.AD+]
__5 strike a stringed instrument with a plectron, [Refs 5th c.BC+]: generally, play any instrument (see. κροῦμα, κρουματικός) [κρούων ἰαστί “Comedy texts Adesp.” 415 ">Refs]: with dative, κ. κρεμβάλοις, ={κρεμβαλίζειν}, [Refs 2nd c.AD+]
__6 κ. τὴν θύραν knock at the door on the outside, [LXX+5th c.BC+].
__7 κ. σταθμὸν ἑτερόζυγον, ={κρουσιμετρέω}, [κρούων γε μὴν αὐτὰς ἐωνούμην 5th c.BC: Eupolis Comicus 184 ">Refs 5th c.BC+].
__8 obscene meaning, [Refs 5th c.BC+].
__9 middle, κρούεσθαι πρύμναν back water, [Refs 5th c.BC+] (also in active, [Refs 2nd c.BC+]: hence κρούεσθαι τὸ πτερόν fly backwards, [Refs 2nd c.AD+] —also in active, [Refs 3rd c.AD+]
__10 κρούειν ἀκράτῳ, see at {πατάσσω} [Refs]

_{LSJ Scripture Refs: LXX.Judg.19.22}