Know how to use "fewer" and "less"? Find out.
Old English geldan (Anglian), gieldan (West Saxon) "to pay" (class III strong verb; past tense geald, past participle golden), from Proto-Germanic *geldanan "pay" (cf. Old Saxon geldan "to be worth," Old Norse gjaldo "to repay, return," Middle Dutch ghelden, Dutch gelden "to cost, be worth, concern," Old High German geltan, German gelten "to be worth," Gothic fra-gildan "to repay, requite").
Perhaps from PIE *ghel-to- "I pay," found only in Balto-Slavic and Germanic, unless Old Church Slavonic zledo, Lithuanian geliuoti are Germanic loan-words. Sense developed in English via use to translate Latin reddere, French rendre, and had expanded by c.1300 to "repay, return, render (service), produce, surrender." Related to Middle Low German and Middle Dutch gelt, Dutch geld, German Geld "money." Yielding in sense of "giving way to physical force" is recorded from 1660s.
Old English gield "payment, sum of money" (see yield (v.)); extended sense of "production" (as of crops) is first attested mid-15c. Earliest English sense survives in financial "yield from investments."