|Origin:||invalidus, from validus; VALID|
a contract, ticket, claim etc that is invalid is not legally or officially acceptable [≠ valid]:
Without the right date stamped on it, your ticket will be invalid.
an argument, reason etc that is invalid is not based on true facts or clear ideas, and lacks good judgment [≠ valid]
if something you type into a computer is invalid, the computer does not recognize or accept it:
Filename in invalid format.