1 the action of pulling sth along a surface; the power that is used for doing this 拖拉；牵引；拉力；牵引力: diesel/electric/steam traction 柴油╱电力╱蒸汽牵引

2 a way of treating a broken bone in the body that involves using special equipment to pull the bone gradually back into its correct place 牵引治疗: He spent six weeks in traction after he broke his leg. 他折断腿以后，花了六个星期作牵引治疗。

3 the force that stops sth, for example the wheels of a vehicle, from sliding on the ground 附着摩擦力（如车轮在地面上的）