Source : WordNet®

loosen up
     v 1: cause to become unblocked; "The medicine unstuffed my nose
          in minutes!" [syn: {unstuff}] [ant: {stuff}]
     2: become less tense, less formal, or less restrained, and
        assume a friendlier manner; "our new colleague relaxed
        when he saw that we were a friendly group" [syn: {relax}]
     3: make one's body limber or suppler by stretching, as if to
        prepare for strenuous physical activity [syn: {limber up},
         {warm up}]
     4: become less tense, rest, or take one's ease; "He relaxed in
        the hot tub"; "Let's all relax after a hard day's work"
        [syn: {relax}, {unbend}, {unwind}, {decompress}, {slow
        down}] [ant: {tense}]
     5: cause to feel relaxed; "A hot bath always relaxes me" [syn:
        {relax}, {unstrain}, {unlax}, {unwind}, {make relaxed}]
        [ant: {tense}, {tense}]