1. In an informal manner.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• informals,
• informallly,
• informall,
• informaly,
• unfortally,
• informallity,
• informatl,
• informail,
• imformally,
• uniformally,
• informalty,
• infomally,
• informlly,
• inofrmally,
• infromally,
• inforamlly,
• informmally,
• informallyy,
• inforoally,
• informly

• informer,
• informing,
• informatics,
• informercial,
• informant,
• informal,
• infirmity,
• informative,
• infernally,
• informality,
• informatory,
• infirmary,
• informatively,
• information,
• informed.

The adjective form of "informally" is "informal".

The plural form of "informally" is "informally". The word remains unchanged in its plural form.

The singular form of the word "informally" is "informal"