Definition

noun

A small quantity of liquid, just large enough to hold its own round shape via surface tension, especially one that falls from a source of liquid.
“Put three drops of oil into the mixture.”
A very small quantity of liquid, or (by extension) of anything.
“asked for just a drop more tea; she was thirsty and there wasn't a drop of water to be found”
(now especially with "the") Alcoholic spirits in general.
“It doesn't matter where you're from; anyone who enjoys the drop is a friend of mine.”

verb

To fall in droplets (of a liquid).
To drip (a liquid).
“The equipment shows how much the glacier has moved and the amount it dropped in height over the summer.”
Generally, to fall (straight down).
“A single shot was fired and the bird dropped from the sky.”