unserious

Unserious is an English adjective that describes someone or something lacking seriousness, gravity, or earnest intent. It can refer to behavior, remarks, attitudes, or content designed to be playful or inconsequential. The word is formed with the prefix un- attached to serious; serious itself derives from Latin serious, meaning weighty, severe, or important. In dictionaries, unserious is defined as not serious or not given to serious consideration.

Usage carries nuance. Unserious can describe lighthearted or humorous conduct, but it can also imply disrespect or unreliability when seriousness is expected. It frequently appears in phrases such as an unserious remark, an unserious tone, or an unserious attitude. The appropriateness of the term depends on context, audience, and register. In formal writing, many editors prefer not serious or phrases like not to be taken seriously rather than using unserious.

Related terms include frivolous, playful, lighthearted, and jaunty. The noun unseriousness is uncommon; speakers more often use not seriousness or frivolity to express a similar idea. See also seriousness, earnestness, and solemnity.