calculate

English calculate was borrowed from Latin calculātus, the perfect passive participle of calculō, meaning "to reckon or compute." That verb comes from calculus, "a pebble," itself formed from calx ("limestone") plus the diminutive suffix -ulus.

The word's core sense has stayed remarkably steady: calculō originally meant reckoning by means of pebbles, and calculate still means to work out a figure or answer — just without the stones.

Calculate shares its root with calculus, the "pebble" word that later became the name of a whole branch of mathematics.