[1] : WordNet (r) 2.0

back down
     v 1: move backwards from a certain position; "the bully had to
          back down" syn: back up, back off
     2: remove oneself from an obligation; "he bowed out when he
        heard how much work was involved" syn: chicken out, back
        off, pull out, bow out
see also:
back up back off chicken out back off pull out bow out 

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

80 moby thesaurus words for "back down":
   abjure, back off, back out, backpedal, backtrack, backwater,
   balance, balk, beat a retreat, beg off, break off combat, cave in,
   cease resistance, climb down, crawfish out, cry off, debate,
   deliberate, demur, deny, disavow, disclaim, disengage, disown,
   draw back, draw off, eat crow, eat humble pie, fall back, falter,
   fear, forswear, give ground, give in, give place, give up,
   give way, go back, go back on, hang back, hem and haw, hesitate,
   hold back, hover, hum and haw, jib, move back, pause, ponder,
   pull back, pull out, quit the field, recall, recant, renege,
   renounce, repudiate, resile, retire, retract, retreat, revoke,
   run back, scruple, shilly-shally, shy, stand back, stick at,
   stickle, stop to consider, straddle the fence, strain at, swallow,
   take back, think twice about, unsay, weasel out, welsh, withdraw,
   yield

Back Down >> B Words
Back Down, definition of term: Back Down
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Back >> B Words
Back, definition of term: Back
back_pag1.html

Back Off >> B Words
Back Off, definition of term: Back Off
back+off_pag1.html

Back Out >> B Words
Back Out, definition of term: Back Out
back+out_pag1.html

Back Up >> B Words
Back Up, definition of term: Back Up
back+up_pag1.html

Back Link >> B Words
Back Link, definition of term: Back Link
back+link_pag1.html

Back End >> B Words
Back End, definition of term: Back End
back+end_pag1.html

Back Country >> B Words
Back Country, definition of term: Back Country
back+country_pag1.html

Back Door >> B Words
Back Door, definition of term: Back Door
back+door_pag1.html

Answer Back >> A Words
Answer Back, definition of term: Answer Back
answer+back_pag1.html