A central defender, a player who plays in the centre of defence, just in front of the goalkeeper(noun)
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Use "centre-back" in a sentence
"Song is a centre-back with class but he's not what you call a centre-back who talks and wants to play there."
"They may have the worst defensive record in the Premier League away from home but this was not evident in the way they kept West Ham out at the last, with Christopher Samba an awesome presence at centre-back."
"Bocanegra's only excuse for a dreadful attempt is that, as a centre-back, he is not accustomed to being in such advanced positions."