Informally

[in-fawr-muh l] /ɪnˈfɔr məl/

adjective
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.
/ɪnˈfɔːməl/
adjective
1.
not of a formal, official, or stiffly conventional nature: an informal luncheon
2.
appropriate to everyday life or use: informal clothes
3.
denoting or characterized by idiom, vocabulary, etc, appropriate to everyday conversational language rather than to formal written language
4.
denoting a second-person pronoun in some languages used when the addressee is regarded as a friend or social inferior: In French the pronoun “tu” is informal, while “vous” is formal
adj.

mid-15c., “lacking form; not in accordance with the rules of formal logic,” from in- (1) “not, opposite of” + formal. Meaning “irregular, unofficial” is from c.1600. Sense of “done without ceremony” is from 1828. Related: Informally.