half back
noun [ C ] uk/ˈhɑːf bæk/ us/ˈhæf bæk/
（足球的二三五阵型中，两名分别位于中场左右两侧的）前卫
one of two football players who play on the left and right side of midfield in teams that use a 2 3 5 system, which consists of two defenders, three midfielders and five forwards