1. Change something so that its value declines; for example, art forms
   "Critics accused the artist of bastardising traditional techniques in his modern works";
   - bastardize
    
2. Declare a child to be illegitimate
   "In medieval times, rulers sometimes bastardised children to prevent them from inheriting";
   - bastardize

Derived forms: bastardised, bastardising, bastardises

Type of: adjudge, corrupt, debase, debauch, declare, demoralise [Brit], demoralize, deprave, hold, misdirect, pervert, profane, subvert, vitiate