Past use doesn’t determine what we mean by uttering a word on a particular occasion, but it does shape what a speaker can intend to get across. If I am being cooperative, and I intend to make a request that you pass something on the table, I won’t use a word I know you don’t know. To do so would be to violate a tacit commitment to a basic principle of cooperation, which Grice argues underpins all communication. – Psyche