spe ‧ cial ‧ ize BrE AmE ( also specialise British English ) /ˈspeʃəlaɪz/ verb [intransitive]
[ Word Family: noun : ↑ special , ↑ specialist , SPECIALITY/SPECIALTY , ↑ specialization , ↑ specialism ; adjective : ↑ special , ↑ specialized ; verb : ↑ specialize ; adverb : ↑ specially ]
to limit all or most of your study, business etc to a particular subject or activity
specialize in
Simmons specialized in contract law.