The noun is pronounced /ɪnvəlɪd/. The adjective is pronounced /ɪnvælɪd/ and is hyphenated in‧val‧id.
1.
An invalid is someone who needs to be cared for because they have an illness or disability.
I hate being treated as an invalid.
N-COUNT
2.
If an action, procedure, or document is invalid , it cannot be accepted, because it breaks the law or some official rule.
The trial was stopped and the results declared invalid...
ADJ
3.
An invalid argument or conclusion is wrong because it is based on a mistake.
We think that those arguments are rendered invalid by the hard facts on the ground.
ADJ