From aqab in its denominative sense; a lier in wait -- heel (by mistake for aqeb).
see HEBREW aqab
see HEBREW aqeb
H6120. aqeb
II. עָקֵב verbal adjective overreacher, Psalm 49:6 יְסֻבֵּנִי עֲקֵבַי עֲוֺן i.e. of those who would take some insidious advantage of me.