mid-14c., pelot, "any little ball," as of a medicine or food, but especially a little metallic ball used as a missile, from Old French pelote "small ball" (11c.) and directly from Medieval Latin pelotis, from Vulgar Latin *pilotta, diminutive of Latin pila "ball, playing ball, the game of ball," perhaps originally "ball of hair," from pilus "hair" (see pile (n.3)).
"head-first dive or plunge," 1849, from head (n.); as a type of pass or shot with the head in soccer, by 1906. Earlier it meant "executioner, headsman" (mid-15c.).
"accumulation; ball," 1620s, from Latin glomerationem (nominative glomeratio), noun of action from past-participle stem of glomerare "to wind or form into a ball, roll together, collect," from glomus "ball of yarn, ball-shaped mass," from Proto-Italic *glemos-, from PIE *glem- or *glom-, perhaps originally "ball," but the reconstruction is uncertain (see glebe).
1774, "action of collecting in a mass," from Latin agglomerationem (nominative agglomeratio), noun of action from past-participle stem of agglomerare "to wind or add onto a ball," from ad "to" (see ad-) + glomerare "wind up in a ball," from glomus (genitive glomeris) "ball, ball of yarn, ball-shaped mass," which is of uncertain origin (see glebe). In reference to a mass so formed, it is recorded from 1833.