Merriam-Webster Collegiate Dictionary - quadrate

 I. adjective  Etymology: Middle English, from Latin quadratus, past participle of quadrare to make square, fit, from quadrum square; akin to Latin quattuor four  Date: 14th century  1. being square or approximately square  2. of a heraldic cross expanded into a square at the junction of the arms — see cross illustration  3. of, relating to, or constituting a bony or cartilaginous element of each side of the skull to which the lower jaw is articulated in most vertebrates below mammals  II. noun  Date: 15th century  1. an approximately square or cubical area, space, or body  2. a ~ bone