WordWeb Online

1. Not suitable for a particular occasion etc
   "noise seems inappropriate at a time of sadness"; "inappropriate shoes for a walk on the beach"; "put inappropriate pressure on them"
    
2. Not in keeping with what is correct or proper
   "completely inappropriate behaviour"
   - incompatible, out of keeping, unfitting

See also: appropriateness, improper, inappropriately, inappropriateness, incongruous, malapropos, unbefitting, wrong

Antonym: appropriate