What is Serious ?
Serious is (adj) 1. not funny; not joking a very serious play He’s such a serious little boy. Stop laughing – it’s very serious. He’s very serious about the pro- posal. The doctor’s expression was very serious. 2. important and possibly dangerous There was a serious accident on the motor- way. The storm caused serious damage. There’s no need to worry – it’s nothing seri- ous. 3. carefully planned The management is making serious attempts to improve work- ing conditions.
source: Easier English, Student Dictionary Upper Intermediate Level