Old English net "netting, network, spider web, mesh used for capturing," also figuratively, "moral or mental snare or trap," from Proto-Germanic *natjan (cognates: Old Saxon net, Old Norse, Dutch net, Swedish nät, Old High German nezzi, German Netz, Gothic nati "net"), originally "something knotted," from PIE *ned- "to twist, knot" (cognates: Sanskrit nahyati "binds, ties," Latin nodus "knot," Old Irish nascim "I bind, oblige").

"remaining after deductions," 1510s, from earlier sense of "trim, elegant, clean, neat" (c.1300), from Old French net "clean, pure," from Latin nitere "to shine, look bright, glitter" (see neat). Meaning influenced by Italian netto "remaining after deductions." As a noun, 1910.