once \once\ o^ns, n. zool.
   the ounce.
   1913 webster

once \once\ wu^ns, adv. oe. ones, anes, an adverbial form
   fr. one, on, an, one. see one-, -wards.
   1. for one time; by limitation to the number one; not twice
      nor any number of times more than one.
      1913 webster

            ye shall . . . go round about the city once. --josh.
                                                  vi. 3.
      1913 webster

            trees that bear mast are fruitful but once in two
            years.                                --bacon.
      1913 webster

   2. at some one period of time; -- used indefinitely.
      1913 webster

            my soul had once some foolish fondness for thee.
                                                  --addison.
      1913 webster

            that court which we shall once govern. --bp. hall.
      1913 webster

   3. at any one time; -- often nearly equivalent to ever, if
      ever, or whenever; as, once kindled, it may not be
      quenched.
      1913 webster

            wilt thou not be made clean? when shall it once be?
                                                  --jer. xiii.
                                                  27.
      1913 webster

            to be once in doubt
            is once to be resolved.               --shak.
      1913 webster

   note: once is used as a noun when preceded by this or that;
         as, this once, that once. it is also sometimes used
         elliptically, like an adjective, for once-existing.
         "the once province of britain." --j. n. pomeroy.
         1913 webster

   at once.
      a at the same point of time; immediately; without delay.
          "stand not upon the order of your going, but go at
          once." --shak. "i . . . withdrew at once and
          altogether." --jeffrey.
      b at one and the same time; simultaneously; in one body;
          as, they all moved at once.

   once and again, once and once more; repeatedly. "a dove
      sent forth once and again, to spy." --milton.
      1913 webster
see also:
one- -wards at once once and again 

ounce \ounce\, n. f. once; cf. it. lonza, sp. onza; prob. for
   lonce, taken as l'once, fr. l. lynx, gr. ?, or an assumed
   fem. adj. lyncea, from lynx. cf. lynx. zool.
   a feline quadruped felis irbis syn. felis uncia
   resembling the leopard in size, and somewhat in color, but it
   has longer and thicker fur, which forms a short mane on the
   back. the ounce is pale yellowish gray, with irregular dark
   spots on the neck and limbs, and dark rings on the body. it
   inhabits the lofty mountain ranges of asia. called also
   once.
   1913 webster ounded
see also:
lynx felis irbis felis uncia once 

once
     adj : belonging to some prior time; "erstwhile friend"; "our
           former glory"; "the once capital of the state"; "her
           quondam lover" syn: erstwhilea, formera, oncea,
            onetimea, quondama, sometimea
     adv 1: on one occasion; "once i ran into her" syn: one time, in
            one case
     2: as soon as; "once we are home, we can rest" syn: when
     3: at a previous time; "once he loved her"; "her erstwhile
        writing" syn: formerly, at one time, erstwhile, erst
see also:
erstwhilea formera oncea onetimea quondama sometimea 
one time in one case when formerly at one time 
erstwhile erst 

88 moby thesaurus words for "once":
   alone, already, ancient, anytime, anyway, anywise, apart,
   at a stroke, at all, at any time, at intervals, at once,
   at one time, at times, at whatever time, before, by itself, bygone,
   conclusively, decidedly, definitely, directly, earlier, early,
   erstwhile, finally, for good, fore, former, formerly, heretofore,
   if ever, immediately, immemorial, in a jiffy, in a trice,
   in a wink, in the singular, individually, instantly,
   just this once, late, long ago, no matter when, now and again,
   occasionally, old, olden, on one occasion, once for all,
   one by one, one day, one fine morning, one time, onetime,
   only once, particularly, past, per se, periodically, positively,
   prehistoric, previous, previously, primeval, primitive, prior,
   promptly, quondam, recent, right away, separately, severally,
   simultaneously, single-handedly, singly, singularly, some time ago,
   sometime, sometimes, sporadically, then, time was, together,
   whenever, whensoever, whilom, without delay

once, adv.  enough.