WordWeb Online

1. According to custom, rule or natural law
   - rule-governed
    
2. Having a legally established claim
   "the true and lawful king";
   - true, rightful
    
3. Authorized, sanctioned by, or in accordance with law
   "a lawful government";
   - legitimate, licit, legit [informal]
    
4. Conformable to or allowed by law
   "lawful methods of dissent"

See also: law-abiding, lawfulness, legal, legitimate, observant, regular, square, straight

Antonym: unlawful

Encyclopedia: Lawful