In, to, or toward the rear: We walked behind. In a place or condition that has been passed or left: I left my gloves behind. In arrears; late: I fell behind in my payments. Below the standard level; in or into an inferior position: Don't fall behind in class. Slow: My watch is running behind. Archaic Yet to come. At the back of or in the rear of: He sat behind her. On the farther side or other side of; beyond: The broom is behind the door. In a place or time that has been passed or left by: Their worries are behind them. Later than: The plane was behind schedule. Used to indicate deficiency in performance: behind us in technological development. Hidden or concealed by: hatred hidden behind a bland smile. In the background of; underlying: Behind your every action is self-interest. In a position or attitude of support: The leaders have the army behind them. In pursuit of: The police were hard behind the escapees. Informal The buttocks.