- The definition of informal is something or someone who is casual or relaxed.
An example of informal used as an adjective is informal clothing, such as comfy casual jeans and a sweatshirt.
An informal poolside party.
- not according to prescribed or fixed customs, rules, ceremonies, etc.
- casual, easy, unceremonious, or relaxed
- designed for use or wear on everyday occasions
- not requiring formal dress
- designating or of the words, phrases, and idioms characteristic of speech or writing that is casual, ordinary, unceremonious, etc.; colloquial
- Not formal or ceremonious; casual: an informal gathering of friends; a relaxed, informal manner.
- Not being in accord with prescribed regulations or forms; unofficial: an informal agreement.
- Suited for everyday wear or use: informal clothes.
- Characterized by nontechnical vocabulary, simple sentence structure, and relatively few explicit transitions, as typified by spoken language: informal discourse.
(comparative more informal, superlative most informal)