Longman Dictionary of Contemporary English homepage

Date: 1500-1600
Language: Latin
Origin: invalidus, from validus; VALID

invalid

1 adjective
     
in‧val‧id1
1 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.
2 an argument, reason etc that is invalid is not based on true facts or clear ideas, and lacks good judgment [≠ valid]
3TD if something you type into a computer is invalid, the computer does not recognize or accept it:
Filename in invalid format.

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