Etymology

From earlier *ha-k(a)r, from Proto-Indo-European *sm̥-kr̥t ‎(“one time”). The first component of a compound is zero-grade of *sḗm, with cognates such as Latin sem-per ‎(“every time, always”) and sem-el ‎(“once”), Ancient Greek εἷς ‎(heîs, “one”) and Sanskrit सकृत् ‎(sa-kṛ́t, “once, at once”).