ˌspɛʃiˈælɪti ˌspɛʃəlɪˈzeɪʃn̩ ˈspɛʃəlti the special line of work you have adopted as your career his specialization is gastroenterology the act of specializing; making something suitable for a special purpose (biology) the structural adaptation of some body part for a particular function cell differentiation in the developing embryo