the.com/rate

means A measure of how much one thing changes compared to another — a price, pace, or proportion, usually per unit of something else.

from From Latin rata (as in pro rata, 'according to the calculated share'), from reri, 'to reckon or calculate.' It came into English through medieval Latin and French in money and tax contexts — a 'rate' was literally a fixed, reckoned amount — before stretching to cover speed, frequency, and quality ('first-rate').