From Middle English seren, seeren, from Old English sēarian (“to become sere, to grow sear, wither, pine away”), from Proto-West Germanic *sauʀēn (“to dry out, become dry”); compare also Proto-Germanic *sauzijaną (“to make dry”). Related to Old High German sōrēn (“to wither, wilt”). See Etymology 1 for more cognates. The use in firearms terminology may relate to French serrer (“to grip”).