make a counterattack and return like for like, especially evil for evil; "The Empire strikes back"; "The Giants struck back and won the opener"; "The Israeli army retaliated for the Hamas bombing"
keep in one's mind; "I cannot retain so much information"
secure and keep for possible future use or application; "The landlord retained the security deposit"; "I reserve the right to disagree"
allow to remain in a place or position; "We cannot continue several servants any longer"; "She retains a lawyer"; "The family's fortune waned and they could not keep their household staff"; "Our grant has run out and we cannot keep you on"; "We kept the work going as long as we could"
hold within; "This soil retains water"; "I retain this drug for a long time"
any backward region that is isolated from the world and resists progress
a body of water that was created by a flood or tide or by being held or forced back by a dam; "the bayous and backwaters are breeding grounds for mosquitos"