WordWeb Online

1. Must previously have happened or existed, happen or be in place during (in order for stated thing to be happening or be the case)
   "success usually requires hard work";
   - necessitate, ask, postulate, need, take, involve, call for, demand
    
2. Consider obligatory; request and expect
   "We require our secretary to be on time";
   - ask, expect
    
3. Make someone do something
   - command
    
4. Have a requirement for
   "This piano requires the attention of a competent tuner";
   - want, need

Derived forms: required, requires, requiring

Type of: be, demand, enjoin, order, say, tell