Pecuniary descends from Latin pecūniārius, from pecūnia (money), from pecū (cattle) — preserving one of the deepest cultural equations in human language: cattle equals wealth. The same PIE root *péḱu- produced English fee, feudalism, peculiar, and the first rune of the Germanic alphabet.
Of, relating to, or consisting of money; having to do with financial matters or monetary penalties.
From Latin 'pecūniārius' (relating to money, financial), derived from 'pecūnia' (money, property, wealth), which in turn comes from 'pecū' or 'pecus' (cattle, livestock, flock), from PIE *peḱu- (wealth in livestock, cattle). The semantic journey from cattle to coined money preserves the ancient Indo-European equation of livestock with portable, countable wealth: cattle were the original store of value, medium of exchange, and unit of account across early agrarian societies. The same PIE root *peḱu- produced Sanskrit 'paśú' (cattle, animal), Gothic 'faihu' (property, money),