peḱu-
“livestock, wealth in cattle”fee, pecuniary, peculiar, fellow
Root yielding Latin pecū/pecūnia, English fee, pecuniary, peculiar, fellow.
Discussion
The PIE noun *peḱu- (livestock, moveable property, wealth in cattle) is one of the most economically significant words in the reconstructed vocabulary — a term that encoded the PIE equation of cattle with wealth, an equation so fundamental that it generated the vocabulary of money itself.
Latin pecū (cattle, livestock) and the derivative pecūnia (money — literally "cattle-wealth") gave English: pecuniary (pertaining to money), impecunious (without money — without cattle), and the archaic peculium (private property, originally a slave's small personal fund). The word peculiar (from pecūliāris, "of one's own property") preserves the private-ownership sense: something peculiar is something distinctly one's own.
The semantic chain cattle → wealth → money is not metaphorical but literal: in the PIE and early IE world, cattle WERE money. Wealth was counted in heads of cattle, debts were paid in livestock, and a person's social standing was measured by the size of their herd. The Latin word for money (pecūnia) preserves this fact as explicitly as any archaeological finding could.
English fee (OE feoh, from PGmc *fehu, from PIE *peḱu-) continues the root natively — a fee was originally a payment in livestock. The word fief (feudal estate — from Medieval Latin feodum, from Frankish *fehu-ōd, "cattle-property") connects to the same root, making the entire feudal system etymologically a cattle-system. German Vieh (cattle, livestock) confirms the Germanic cognate.
Sanskrit páśu- (cattle, livestock, animal) preserves the Indo-Iranian reflex. The Vedic term paśu-bandha ("cattle-bond" — a type of animal sacrifice) shows the word in ritual context.
Old Irish cet (property), if connected, would provide Celtic attestation.
The Gothic cognate faihu (property, money) appears in the runic alphabet: the first rune ᚠ is named *fehu (cattle/wealth), beginning the alphabet with the concept of prosperity. The PIE speakers who named their cattle generated a word that would name their money, their feudal estates, their professional fees, and the first letter of their alphabet.