1. Bound by or as if by an oath
   "according to an early tradition became his pledged brother";
   - sworn

1. Promise solemnly and formally
   "I pledge that I will honour my wife";
   - plight [archaic]
    
2. Give as a guarantee
   "I pledge my honour"
    
3. Bind or secure by a pledge
   "I was pledged to silence"
    
4. Pay (an amount of money) as a contribution to a charity or service, especially at regular intervals
   "I pledged $10 a month to my favourite radio station";
   - subscribe
    
5. Propose a toast to
   "They pledged the newlyweds";
   - toast, drink, salute, wassail [archaic]

See also: committed

Type of: assure, bind, charge, consign, donate, fete, fête, hold, honor [US], honour [Brit, Cdn], obligate, oblige, promise, reward

Encyclopedia: Pledge