AT prep.
, Home, Large, Last (phrase and syn.), Length, Once, etc. -- At it, busily or actively engaged. -- At least. See Least and However. -- At one. See At one, in the Vocabulary.
BACK v.
nd deny. [Colloq.] -- To back out, To back down, to retreat or withdraw from a promise, engagement, or contest; to recede. [Colloq.] Cleon at first . . . was willing to go; but, finding that he [Nicias] was in earnest, he tried to back out. Jowett (Thucyd. )