[1] : WordNet (r) 2.0

keep up
     v 1: maintain a required pace or level; "he could not keep up and
          dropped out of the race"
     2: lengthen or extend in duration or space; "we sustained the
        diplomatic negociations as long as possible"; "prolong the
        treatment of the patient"; "keep up the good work" syn: prolong,
         sustain
     3: keep in safety and protect from harm, decay, loss, or
        destruction; "we preserve these archeological findings";
        "the old lady could not keep up the building"; "children
        must be taught to conserve our national heritage"; "the
        museum curator conserved the ancient manuscripts" syn: conserve,
         preserve, maintain
     4: keep informed; "he kept up on his country's foreign
        policies" syn: keep abreast, follow
     5: prevent from going to bed at night; "the anticipation of the
        trip kept the children up all night"; "i kept myself up
        all night studying for the exam"
see also:
prolong sustain conserve preserve maintain keep abreast 
follow 

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

123 moby thesaurus words for "keep up":
   afford support, au courant, back, back up, be employed, bear,
   bear up, bolster, bolster up, brace, buoy up, buttress, carry,
   carry on, carry on business, conserve, continue, copyright, cradle,
   crutch, cushion, do business, endure, extend, follow a trade,
   follow the crowd, follow the fashion, give support, go on, guard,
   hang in, hang tough, have a job, hold, hold out, hold up,
   join the parade, keep, keep account of, keep afloat, keep alive,
   keep at, keep at it, keep count of, keep driving, keep going,
   keep in step, keep informed, keep intact, keep inviolate, keep on,
   keep pace with, keep posted, keep safe, keep track of, keep trying,
   keep up appearances, keep up on, keep up with, labor, last,
   lend support, lengthen, mainstay, maintain, moonlight,
   never say die, not accept compromise, not destroy, not endanger,
   not expend, not flag, not give up, not use up, not waste,
   not weaken, patent, perpetuate, persevere, persist, pillow,
   practice a profession, preserve, prolong, prop, protect, protract,
   register, reinforce, retain, save, see it out, set up shop, shore,
   shore up, shoulder, spare, stand up, stay, stay briefed,
   stay employed, stay it out, stay the distance, stick it out,
   subsidize, subvention, support, sustain, sweat it out, take it,
   toil, transact business, underbrace, undergird, underlie, underpin,
   underset, upbear, uphold, upkeep, work, work at, work for

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Bang Up, definition of term: Bang Up
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Backed Up, definition of term: Backed Up
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Back Up, definition of term: Back Up
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Ante Up, definition of term: Ante Up
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Act Up, definition of term: Act Up
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