1. promise, assurance, word, word of honor, Archaic. troth, vow, oath, sworn statement, Archaic. plight; endorsement, testimonial, attestation; contract, compact, covenant, obligation, engagement, agreement; guarantee, guaranty, warrant, warranty, Law. covenant of warranty, Law. warranty deed, Obs. vouch.
2. collateral, surety, Law. security, earnest, deposit, Law. earnest money; pawn, gage, bail, Insurance. bond, Law. mortgage, Law. mortgage bond, Law. bail bond, Rare. hostage.
3. tentative member, newcomer, initiate, neophyte, beginner, catechumen.
4. toast, salute, cheer.
5. engage, bind, adjure, draft; press, compel, oblige, require, charge, command, enjoin.
6. plight, affiance, betroth; promise, give one's solemn word or promise, vow, state on one's honor, swear to, state under oath; assure, offer assurance, asseverate, avouch, aver, affirm.
7. guarantee, ensure, secure, Finance. bond, Law. mortgage; pawn, Rare. impawn, gage, put up collateral, give earnest money, make a deposit, obligate; warrant, vouch, attest to, testify to, endorse; contract, covenant, enter an agreement, make a bargain or deal, shake on it.
8. toast, drink to, drink to the health of, salute, give three cheers, cheer.

A Note on the Style of the synonym finder. 2014.