serious

adjective

1. 1

   causing fear or anxiety by threatening great harm

   a dangerous operation

   a grave situation

2. 2

   requiring effort or concentration; complex and not easy to answer or solve

   raised serious objections to the proposal

   the plan has a serious flaw

3. 3

   of great consequence

   marriage is a serious matter

4. 4

   appealing to the mind

   good music

   a serious book

5. 5

   concerned with work or important matters rather than play or trivialities

   a serious student of history

   a serious attempt to learn to ski

6. 6

   completely lacking in playfulness