[1] : The Collaborative International Dictionary of English v.0.48

undertake \un`dertake"\, v. t. imp. undertook; p. p.
   undertaken; p. pr.  vb. n. undertaking. under + take.
   1. to take upon one's self; to engage in; to enter upon; to
      take in hand; to begin to perform; to set about; to
      attempt.
      1913 webster

            to second, or oppose, or undertake
            the perilous attempt.                 --milton.
      1913 webster

   2. specifically, to take upon one's self solemnly or
      expressly; to lay one's self under obligation, or to enter
      into stipulations, to perform or to execute; to covenant;
      to contract.
      1913 webster

            i 'll undertake to land them on our coast. --shak.
      1913 webster

   3. hence, to guarantee; to promise; to affirm.
      1913 webster

            and he was not right fat, i undertake. --dryden.
      1913 webster

            and those two counties i will undertake
            your grace shall well and quietly enjoiy. --shak.
      1913 webster

            i dare undertake they will not lose their labor.
                                                  --woodward.
      1913 webster

   4. to assume, as a character. obs. --shak.
      1913 webster

   5. to engage with; to attack. obs.
      1913 webster

            it is not fit your lordship should undertake every
            companion that you give offense to.   --shak.
      1913 webster

   6. to have knowledge of; to hear. obs. --spenser.
      1913 webster

   7. to take or have the charge of. obs. "who undertakes you
      to your end." --shak.
      1913 webster

            keep well those that ye undertake.    --chaucer.
      1913 webster
see also:
undertook undertaken undertaking 

[2] : The Collaborative International Dictionary of English v.0.48

undertake \un`dertake"\, v. i.
   1. to take upon one's self, or assume, any business, duty, or
      province.
      1913 webster

            o lord, i am oppressed; undertake for me. --isa.
                                                  xxxviii. 14.
      1913 webster

   2. to venture; to hazard. obs.
      1913 webster

            it is the cowish terror of his spirit
            that dare not undertake.              --shak.
      1913 webster

   3. to give a promise or guarantee; to be surety.
      1913 webster

            but on mine honor dare i undertake
            for good lord titus' innocence in all. --shak.
      1913 webster

[3] : WordNet (r) 2.0

undertake
     v 1: enter upon an activity or enterprise syn: set about, attempt
     2: accept as a challenge; "i'll tackle this difficult task"
        syn: tackle, take on
     3: promise to do or accomplish; "guarantee to free the
        prisoners" syn: guarantee
     4: enter into a contractual arrangement syn: contract
     5: accept as a charge syn: take in charge
     also: undertook, undertaken
see also:
set about attempt tackle take on guarantee contract 
take in charge undertook undertaken 

[4] : Moby Thesaurus II by Grady Ward, 1.0

115 moby thesaurus words for "undertake":
   accept, accept obligation, agree, agree to, answer for, approach,
   assay, assume, attack, attempt, bargain, bargain for,
   be answerable for, be responsible for, be security for, begin,
   bind, buckle to, carry on, certify, chance, commence, commit,
   compact, conduct, contract, covenant, dive into, do, do a deal,
   embark in, embark on, embark upon, employ, endeavor, engage,
   engage in, enter on, enter upon, essay, exercise, fall into,
   fall to, follow, get busy, get cracking, get going, get under way,
   get with it, go about, go at, go bail for, go in for, go into,
   go to it, go upon, guarantee, have an understanding, have at,
   hop to it, jump to it, launch forth, launch into, lay about,
   lift a finger, light into, make a deal, make an attempt,
   make an effort, move into, obligate, offer, pass, pitch in,
   pitch into, pledge, plunge into, practice, proceed to, promise,
   prosecute, pursue, sail into, seek, set about, set at, set forward,
   set going, set to, set to work, shake hands on, specialize in,
   stand back of, start, start in, stipulate, strive, struggle, swear,
   tackle, take on, take the vows, take to, take up, try, turn to,
   use, venture, venture on, venture upon, vow, wade into, wage,
   warrant, work at

Undertake >> U Words
Undertake, definition of term: Undertake
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