informal
- 1Relaxed in manner or style, without the ceremony or strict conventions of a formal occasion.
Their meeting was informal, with everyone sitting on couches instead of around a conference table.
She prefers an informal teaching style that lets students ask questions at any time.
Similarcasual, relaxed, easygoing, unceremonious, laid-back
Oppositeformal, ceremonious, stiff
Note
The everyday sense, built transparently from in- 'not' and formal. It compares with more and most (more informal, never informaler). It can describe an occasion (an informal get-together) or a manner: W. B. Maxwell's bishop in The Mirror and the Lamp (1918) wins attention 'by his informal method.' Informal coaches are family members who teach without any appointment, a use that leans toward the 'unofficial' meaning.
- 2Describing language that belongs to everyday, casual speech rather than formal or ceremonious contexts.
Many dictionaries mark slang and casual contractions as informal.
The letter's informal tone felt out of place in a legal document.
Similarcolloquial, conversational, casual, familiar, chatty
Note
Applied to language, the word sorts names, words and tone by where they are at home rather than by what they mean. Saranka Maheswaran (2025) calls Kollywood 'the informal name for Tamil cinema.' That is the name people actually use in conversation, set beside the official one. An informal name or word is not wrong. It belongs to a particular setting, and choosing it well means matching it to the occasion.
- 3
- 4Not done according to the usual rules, official procedures, or required regulations.
The two countries reached an informal agreement that carried no legal force.
He raised the complaint through an informal channel rather than filing official paperwork.
Similarunofficial, irregular, unwritten
Oppositeofficial, formal, authorized
- 5Not organized into a planned structure; happening without a set arrangement or system.
The market grew up as an informal network of small traders with no central organization.
Their informal planting scheme let the vegetables spread wherever there was open space.
Similarloose, unstructured, unplanned
Oppositestructured, organized, formal, systematic
Note
In horticulture the word describes planting that follows no laid-out plan, such as a scheme that lets vegetables spread into open space rather than keeping to set beds. Business and agriculture use it the same way for cropping patterns, markets, settlements and trading networks that grow up ad hoc. These arrangements are not regulated or designed, so here the contrast with formal is about structure, not manners.
Practice
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Origin
Formed from the prefix "in-" combined with "formal."