gain

\ \ [15] Gain is Germanic in origin, although English acquired it via Old French. Its distant ancestor is the Germanic noun *waithā. The etymological meaning of this was ‘hunting ground’ (it came ultimately from a prehistoric Indo-European base *wei-, which also produced Lithuanian vyti ‘pursue, hunt’ and Sanskrit veti, vayati ‘seeks, follows’), but gradually this extended via ‘place where food or fodder is sought’ to ‘grazing place’ (its modern German and Dutch descendant weide means ‘pasture’).

\ \ From it was formed a verb *waithanjan ‘hunt’ and ‘graze, pasture’, which Vulgar Latin took over as *gwadanjāre. This preserved the semantic dichotomy that had grown up in Germanic: the agricultural sense developed to ‘cultivate land’, and it appears that the ‘hunting’ sense gave rise metaphorically to ‘win, earn’.

\ \ Both passed into Old French gaaigner, but evidently by the time English acquired the word, the former meaning had all but died out (although it is interesting to note that it was introduced into English as a pseudo-archaism in the 17th and 18th centuries: ‘Of old to gain land was as much as to till and manure it’, Termes de la ley 1708).