ἴσημι, found only in the Doric form ἴσαμι, to know; from which some derive the forms ἴστε and ἴσμεν, contracted from ἴσατε and ἴσαμεν; but these forms are more correctly derived from εἴδω, ἴσμεν i. q. ἴδμεν, etc. (cf. Bttm. Ausf. Spr. i. p. 548); on the phrase ἴστε [R ἐστε] γινώσκοντες, Eph. v. 5, see γινώσκω, I. 2 b.
1) to know
Assumed by some as the base of certain irregular forms of G1942; to know
KJV Usage: know.