adj

invalid

ihn-VAL-ihd

adj

Not legally or officially acceptable; not valid.

"Your passport is invalid because it expired last year."

"The referee ruled the goal invalid due to an offside."

noun

A person who is chronically ill, disabled, or too weak to care for themselves.

"He spent his final years as an invalid, cared for by his daughter."

How to Use Invalid

Learner’s notes

In plain EnglishEither "not valid/acceptable" (adjective) or an old-fashioned word for a sick or disabled person (noun).

Common mistake

Note the stress shift: "IN-valid" (noun, a sick person) vs "in-VAL-id" (adjective, not valid).

When to use it

The noun sense ("an invalid") is now considered old-fashioned and can sound insensitive; more neutral terms are preferred today.

Common pairings

invalid argument invalid password declared invalid

more invalid comparative, invalided past tense, invalids plural, invalids singular, most invalid superlative

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Can you complete this real example?

Your passport is _____ because it expired last year.

From in- ("not") + valid, from Latin validus ("strong").

valid Walid Khalid squalid