WordWeb Online

1. Must happen, have or exist previously or during (in order for stated thing to be happen 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