means A premise is an idea or statement you take as a starting point, from which other conclusions or actions are supposed to follow.

from From the Latin praemissa, 'things sent before' or 'set forth beforehand' — from prae- ('before') plus mittere ('to send'). It came into English through medieval logic, where the praemissae were the statements placed at the head of an argument, before the conclusion. The plural 'premises' meaning 'a building' branches from the same root in a roundabout way: legal documents would refer back to property 'aforementioned' — the premises set out earlier — until the word slid over to mean the thing itself.