l]
| 1. | without formality or ceremony; casual: an informal visit. |
| 2. | not according to the prescribed, official, or customary way or manner; irregular; unofficial: informal proceedings. |
| 3. | suitable to or characteristic of casual and familiar, but educated, speech or writing. |
| 4. | Grammar. characterizing the second singular pronominal or verbal form, or its use, in certain languages: the informal tu in French. |