(AREA) [noun] [U] [esp. US] [informal] - the subject in which a person or group has a lot of knowledge or influenceAntiques are very much her turf.(esp. US informal) A group's turf is also the area which it considers its own.The gang defended its turf against the newcomers in the neighbourhood.The gymnastics team won the championship on home turf.
TURF
Meaning of TURF in English
Cambridge English vocab. Кембриджский английский словарь. 2012