WordWeb Online

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
   "keep up the good work";
   - prolong, sustain
    
3. Keep in safety and protect from harm, decay, loss, or destruction
   "The old lady could not keep up the building";
   - conserve, preserve, maintain
    
4. Keep informed
   "He kept up on his country's foreign policies";
   - keep abreast, follow
    
5. Prevent from going to bed at night

Derived forms: keeps up, keeping up, kept up

See also: keep

Type of: bear on, carry on, continue, keep, preserve, uphold