pledge

[1]	swear , vow , promise , give one's word (of honour) , contract , undertake , agree , vouch , vouchsafe
[2]	deposit , plight , pawn , mortgage , (Archaic) gage , (Colloq) (US/Canadian) hock
[3]	toast , subscribe , drink (to) , drink (someone's) health
[4]	toast , drink , salute , wassail

[1]	promise , oath , vow , word (of honour) , covenant , assurance , guaranty , guarantee , warrant , warranty
[2]	bail , surety , collateral , security , deposit , earnest (money) , pawn , gage , bond , guaranty , guarantee
[3]	toast , toast , tribute , cheer , health
[4]	assurance