(manner) In a serious or literal manner. / Gravely; deeply; very much. / Used to attempt to introduce a serious point in a less serious conversation.

The state or quality of being serious.

plural of seriousness

(nonstandard) comparative form of serious: more serious

(idiomatic) Directs attention to immediately preceding failed attempt at humor.

(transitive) To consider (something /what somebody is saying) important and meaningful.

The state of being self-serious.