| adjective | concerned with work or important matters rather than play or trivialities “a serious student of history” |
| adjective | of great consequence “marriage is a serious matter” |
| adjective | causing fear or anxiety by threatening great harm “a dangerous operation” |
| adjective | appealing to the mind “good music” |
| adjective | completely lacking in playfulness |
| adjective | requiring effort or concentration; complex and not easy to answer or solve “raised serious objections to the proposal” |
| seriousness | noun | the trait of being serious; - Robert Rice |
| dangerousness | noun | the quality of not being safe |
| severeness | noun | used of the degree of something undesirable e.g. pain or weather |
| goodness | noun | that which is pleasing or valuable or useful |
| soberness | noun | a manner that is serious and solemn |