Abbott-Smith Manual Greek Lexicon
καθ-ήκω (G2520)
2 καθ-ήκω , [in LXX: impers., Le 5:10 , Ez 21:27 ( 32 ), al. ( מִשְׁפָּט ); τὰ κ. , Ex 5:13 , al. ( דָּבָר ), etc.;] to come down , come to . to be fit , proper : impers., c. acc. et inf., Ac 22:22 (on the tense, v. Bl., § 63, 4); τὰ μὴ καθήκοντα , Ro 1:28 .†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain