Word
invalid
Phoneticsin·valid
/ˈɪnvəɫəd/
Definitions
01not legally or logically correct
B1 · Intermediate
adj. not true, correct, or acceptable according to the rules.
adj. lacking legal force or logical validity; null and void.
“The website said my password was invalid because I used the wrong characters.”
“The contract was declared invalid by the court because one of the signatures had been forged.”
Usage
The stress is on the second syllable: in-VAL-id.
Pitfall
The password was unvalid.
The password was invalid.
The prefix for 'valid' is 'in-', not 'un-'.
02to release from duty due to illness
C1 · Advanced British English · Formal
v. to officially allow someone to leave the army or a job because they are too sick to work.
v. to remove someone from active duty, particularly in a military context, due to injury or chronic ill health.
“The soldier was invalided out of the army after losing his sight in the war.”
“He was eventually invalided home after contracting a tropical fever that left him unable to perform his duties.”
Usage
Usually appears in the passive voice as 'to be invalided out'.
Teaching tip
This is a specialized term mostly found in historical or military literature.
Real-World Examples
“The Indian government has never recognised the agreement and considers it illegal and invalid.” Etymology
From in- + valid.
From Middle French invalide, from Latin invalidus (“infirm, weak”), from in- (“not”) + validus (“strong”).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
- Exam level
- CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.B2 FirstIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.5.5–6.5TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 4.0–4.572–94TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.785–944
- Frequency
- Frequent
- Level
- B2 · Upper Intermediate
- Updated
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