  A pair of conjugate observables, such as the quadrature amplitudes of
harmonic motion, have fundamental fluctuations which are bound by the
Heisenberg uncertainty relation. However, in a squeezed quantum state,
fluctuations of a quantity can be reduced below the standard quantum limit, at
the cost of increased fluctuations of the conjugate variable. Here we prepare a
nearly macroscopic moving body, realized as a micromechanical resonator, in a
squeezed quantum state. We obtain squeezing of one quadrature amplitude $1.1
\pm 0.4$ dB below the standard quantum limit, thus achieving a long-standing
goal of obtaining motional squeezing in a macroscopic object.
