Other forms: hourglasses
An hourglass is the old glass timer through which sand falls from one bulb to another. Turn the hourglass, an hourglass timer, the sand ran out.
The narrow waist controls the rate, and turning it starts it again. Egg timers are small hourglasses. The shape gives hourglass figure, meaning a body narrow at the waist, which is the commonest use of the word. Note that an hourglass takes an rather than a, because the h is silent; and that hourglasses were used at sea to time watches and to measure a ship's speed with a log line.
1nounhourglassA glass timer through which sand falls from one bulb to another.
“When the sand in the hourglass runs out, your turn is over.”
hourglass is a timer.
The word is a plain compound of hour and glass, recorded from the fifteenth century. The device is older than the name and was one of the few reliable ways to measure time at sea, where a pendulum clock is useless.
From hour + glass.
Etymology from Wiktionary, CC BY-SA