Abbott-Smith Manual Greek Lexicon
ἐκούσιος (G1595)
1 ἐκούσιος , -ον ( έκών ), [in LXX chiefly for נְדָבָה , as Nu 15:3 ( κατ’ ἑ. );] usually of actions, voluntary : κατὰ ἑ. , of free will (Lft., in l), Phm 14 .†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain