Word
incompatible
Phoneticsin·com·pat·i·ble, stress on the third syllable
US/ˌɪnkəmˈpætəbəɫ/
UK/ɪnkəmpˈætəbəl/
Definitions
01unable to coexist
B2 · Upper Intermediate
adj. describes two things that are so different they cannot exist or work together at the same time.
adj. describes two or more things that are incapable of existing together in harmony or working in conjunction due to fundamental differences.
“Their personalities were incompatible, so they decided to stop working together.”
“The new software update proved incompatible with the older operating system, causing the entire network to crash during the migration.”
Usage
often used with the preposition 'with'
Synonyms
Antonyms
02chemical/medical reaction
C1 · Advanced Science Technical
adj. describes chemicals or medicines that cause a bad reaction if you mix them.
adj. incapable of being combined without undergoing a chemical change or producing an undesirable medical effect.
“The two cleaning liquids are incompatible and could create dangerous fumes if mixed.”
“The pharmacist warned that the two medications were chemically incompatible and must be administered at least four hours apart.”
Usage
typically used in medical or laboratory contexts
Teaching tip
This is a specialized use; in everyday English, 'incompatible' usually refers to people or technology.
Synonyms
Antonyms
03conflicting things
C2 · Proficiency Countable noun Formal · Technical
n. a person or thing that cannot be combined with another.
n. a person or thing that is fundamentally different from or unable to coexist with another; often used in the plural to describe substances that react poorly together.
“The lab report listed several incompatibles that should never be stored in the same cabinet.”
“In the study of logic, the two propositions were treated as incompatibles, as the truth of one necessitated the falsehood of the other.”
Usage
most commonly found in medical or scientific literature in the plural form
Teaching tip
The noun form is quite rare compared to the adjective; students should focus on the adjective first.
Synonyms
Real-World Examples
“Spain missed the official January 10th 2026 EU transposition deadline, creating legal friction with Brussels over aligning domestic banking rules which the EU says are incompatible with the new regulations.” “Even professional monitoring programs still struggle with limited staff, outdated software or incompatible standards, further slowing the flow of data.” Etymology
Borrowed from French incompatible.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Word family
NOUN
ADJECTIVE
Domains
- 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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englishreference.com/q/incompatible