n. premature fusion of some of the cranial bones, usually before birth, so that the skull is unable to expand in certain directions to assume its normal shape under the influence of the growing brain. Depending on which cranial *sutures fuse early, the skull may become elongated from front to back, broad and short, peaked (oxycephaly or turricephaly), or asymmetrical. Craniosynostosis is a feature of several related inherited disorders (see acrocephalosyndactyly). Compare craniostenosis.... craniosynostosis