specialisation in WordNet English dictionary

1. (biology) the structural adaptation of some body part for a particular function
   "cell differentiation in the developing embryo"
   specialization  specialisation  differentiation 
   
2. the special line of work you have adopted as your career
   "his specialization is gastroenterology"
   specialization  specialisation  specialty  speciality  specialism 
   
3. the act of specializing; making something suitable for a special purpose
   specialization  specialisation 
   

specialisation in English Wiktionary