| Noun | 1. | byproduct - a secondary and sometimes unexpected consequenceconsequence, effect, result, upshot, outcome, event, issue - a phenomenon that follows and is caused by some previous phenomenon; "the magnetic effect was greater when the rod was lengthwise"; "his decision had depressing consequences for business"; "he acted very wise after the event" epiphenomenon - a secondary phenomenon that is a by-product of another phenomenon | |