The unexpected turns a word can take between one use and another.
calculate (v.)
Collection
Words That Changed Shape
To calculate is to work something out with numbers. The Latin calculare meant to reckon, and it was built on calculus, a small pebble, from calx, limestone.1
The pebbles were counters. On a Roman counting board they were moved along grooves to hold the figures of a sum.12
English took calculate in the 1560s. A century later calculus became the name of a method in mathematics.1
Medicine kept the stone. Since the early eighteenth century a calculus has been a stone formed in the body, such as a kidney stone, and dentists use the word for hardened plaque.1
The limestone kept its name too. When Humphry Davy isolated a new metal in 1808, he called it calcium, after calx.3
She calculated how long the journey would take.