Source : WordNet®

deflation
     n 1: (geology) the erosion of soil as a consequence of sand and
          dust and loose rocks being removed by the wind; "a
          constant deflation of the desert landscape"
     2: a contraction of economic activity resulting in a decline of
        prices [ant: {inflation}, {disinflation}]
     3: the act of letting the air out of something [ant: {inflation}]