ex·per·tise 
/ˌɛkspɚˈti:z/ noun
/ˌɛkspɚˈti:z/ noun [noncount] : special skill or knowledge : the skill or knowledge an expert has
▪ His expertise on defense will help the team. ▪ her expertise in legal matters ▪ The company has no environmental expertise. [=the company does not have experience with environmental problems, matters, etc.] ▪ This question falls outside my area of expertise. [=the subject area I know a lot about]
▪ His expertise on defense will help the team. ▪ her expertise in legal matters ▪ The company has no environmental expertise. [=the company does not have experience with environmental problems, matters, etc.] ▪ This question falls outside my area of expertise. [=the subject area I know a lot about]
