Looking up...
disallow
/ˌdɪsəˈlaʊ/
officially refuse to permit
The school board decided to disallow the use of mobile phones during classes.
The school board officially refused to permit students to use mobile phones during classes.
formal
to officially refuse to allow something
The new policy disallows smoking in all indoor areas of the building.
The new policy officially refuses to permit smoking in all indoor areas of the building.
The judge disallowed the evidence because it was obtained illegally.
The judge officially refused to allow the evidence because it was obtained illegally.
Commonly used in legal, administrative, or institutional contexts to indicate an official prohibition.
Pro Tip
Formal vs. Informal Alternatives
Use 'disallow' in formal writing or official contexts (e.g., policies, laws). For everyday situations, 'forbid' or 'ban' may sound more natural.
Gold Rule
Avoid Redundancy
Do not use 'disallow' with 'not' (e.g., 'disallow not' is incorrect). It already conveys negation.
Word Origin
From Middle English *disallowen*, from Old French *desalouer* (to disapprove, reject), from *des-* (do the opposite of) + *alouer* (to approve, allow), from Latin *adlaudāre* (to praise), from *ad-* (to) + *laudāre* (to praise). The sense of refusal emerged in the 15th century.
Usage Notes
Disallow is more formal than forbid or prohibit and is often used in official or legal contexts. It implies an authoritative decision rather than a general restriction.
Word Breakdown
dis-
prefix meaning 'not' or 'opposite of'
prefixallow
to permit or let happen
rootEnglish Dictionary