/gɑ:d ||; gɑrd/noun1 [C] a person who protects a place or people, or who stops prisoners from escaping 警恒: a security guard 保安人员 ☞ Look at warder and bodyguard. 参看warder及bodyguard。
2 [U] the state of being ready to prevent attack or danger 警戒；守恒: Soldiers keep guard at the gate. 大门那里有士兵站岗。Who is on guard ? 谁在值勤？The prisoner arrived under armed guard. 犯人由武装人员押送来了。a guard dog 看门狗
3 [sing] [with.sop] a group of soldiers, police officers, etc who protect sb/sth 一队警恒: The president always travels with an armed guard. 总统出行总是带着一帮子荷枪实弹的警恒。
4 [C] (often in compounds 常用于构成复合词) something that covers sth dangerous or protects sth 防护装置: a fireguard 炉挡a mudguard (= over the wheel of a bicycle) （自行车轮胎上的）挡泥板
5 (US 美 conductor) [C] a person who is in charge of a train but does not drive it 列车长
6 [U] a position that you take to defend yourself, especially in sports such as boxing （尤指拳击等运动中的）防御姿势
off/on (your) guard not ready/ready for an attack, surprise, mistake, etc 没提防，提防（攻击、意外的事、错误等）:
The question caught me off (my) guard and I didn't know what to say. 这问题问得很突然，我不知道该怎么回答。