to take upon oneself, as a task, performance, etc.; attempt

She undertook the job of answering all the mail.

to promise, agree, or obligate oneself (fol. by an infinitive)

The married couple undertook to love, honor, and cherish each other.

to warrant or guarantee (fol. by a clause)

The sponsors undertake that their candidate meets all the requirements.

to take in charge; assume the duty of attending to

The lawyer undertook a new case.

Archaic . to engage oneself by promise; give a guarantee, or become surety.

verb

abstain , forego , forget

verb

address oneself , agree , answer for , bargain , begin , commence , commit , commit oneself , contract , covenant , devote , embark , endeavor , enter upon , fall into , go about , go for , go in for , go into , guarantee , have a hand in , have a try , hazard , initiate , launch , make a run at , move , offer , pitch in , pledge , promise , set about , set in motion , set out , shoulder , stake , stipulate , tackle , take on , take the plunge , take upon oneself , try , try out , venture , volunteer , incur , take over , engage , approach , enter , get off , inaugurate , institute , lead off , open , set to , take up , accept , assume , attempt , dare , execute , grant , overtake , perform , seek , seize , start , strive