STRONGS NT 2467: ἴσημι

ἴσημι, found only in the Doric form ἴσαμι, to know; from which some derive the forms ἴστε and ἰσμεν, contracted from ἰσατε and ἰσαμεν; but these forms are more correctly derived from εἰδῶ, ἰσμεν equivalent to ἴδμεν, etc. (cf. Alexander Buttmann (1873) Ausf. Spr. i., p. 548); on the phrase ἴστε (R ἐστε) γινώσκοντες, Ephesians 5:5, see γινώσκω, I. 2 b.