Source : WordNet®

slow up
     v 1: become slow or slower; "Production slowed" [syn: {slow}, {slow
          down}, {slack}, {slacken}]
     2: cause to proceed more slowly; "The illness slowed him down"
        [syn: {slow}, {slow down}]
     3: lose velocity; move more slowly; "The car decelerated" [syn:
         {decelerate}, {slow}, {slow down}, {retard}] [ant: {accelerate}]