Hebrew

ˀḥr - to be behind; pi - to delay, to detain (HALOT 34–35)

Cf. ˀaḥărōn - at the back; later on; last (HALOT 36).

PS
*ˀḫr - to be different; to be late (DRS 15, HALOT 34‒36, Kogan 2015: 388)