specialization

英[,speʃəlaɪ'zeɪʃən] 美[,spɛʃəlɪ'zeʃən]

1. the act of specializing; making something suitable for a special purpose

2. the special line of work you have adopted as your career;

"his specialization is gastroenterology"

3. (biology) the structural adaptation of some body part for a particular function;

"cell differentiation in the developing embryo"