spear n.1

Old English spir "a sprout, shoot, spike, blade, tapering stalk of grass," from Proto-Germanic *spiraz (source also of Old Norse spira "a stalk, slender tree," Dutch spier "shoot, blade of grass," Middle Low German spir "a small point or top"), from PIE *spei- "sharp point" (see spike (n.1)). Meaning "tapering top of a tower or steeple" first recorded 1590s (a sense attested in Middle Low German since late 14c. and also found in the Scandinavian cognates).

early 14c., "rafter;" late 14c., "stout pole," from or cognate with Middle Low German or Middle Dutch sparre, from Proto-Germanic *sparron (source also of Old English *spere "spear, lance," Old Norse sperra "rafter, beam," German Sparren "spar, rafter"), from PIE root *sper- (1) "spear, pole" (see spear (n.1)). Nautical use, in reference to one used as a mast, yard, boom, etc., dates from 1630s. Also borrowed in Old French as esparre, which might be the direct source of the English word.