WordWeb Online

1. Compliant and obedient to authority
   "editors and journalists who express opinions in print that are opposed to the interests of the rich are dismissed and replaced by subservient ones"
    
2. Serving or acting as a means or aid
   "subservient in solving the crime";
   - implemental, instrumental
    
3. Abjectly submissive; characteristic of a slave or servant
   "she has become submissive and subservient";
   - slavish, submissive

See also: helpful, servile, subordinate