Invalid

Invalid may refer to:

• Patient, a sick person
• one who is confined to home or bed because of illness, disability or injury (sometimes considered a politically incorrect term)
• .invalid, a top-level Internet domain not intended for real use

Look up invalid in Wiktionary, the free dictionary.

As the opposite of valid:

• Validity, in logic, true premises cannot lead to a false conclusion
• Validity (statistics), a measure which is measuring what it is supposed to measure