A member of a broad class of hypothetical elementary particles moving with non-relativistical speeds at the time of structure formation in the early Universe. WIMPs have nonzero rest mass and participate only in the weak nuclear interaction. WIMPs are expected to have collapsed into a roughly isothermal, spherical halo within which the visible portion of our galaxy resides. → dark halo. The → neutralino, predicted by supersymmetric theories is the favorite WIMP candidate. Another candidate is the → axion. WIMPs are candidates for dark matter.