a person who rides a horse, bicycle or motorcycle 骑手；骑马（或自行车、摩托车）的人 
Three riders (= people riding horses) were approaching. 三个骑马的人越来越近。 horses and their riders 马匹及其骑手 She's an experienced rider. 她是位有经验的骑手。 a motorcycle dispatch rider 骑摩托车的通信员
- rider (to something)
an extra piece of information that is added to an official document 公文的附加材料；附文 He finally agreed to a divorce with the rider that she could not remarry. 他最终同意与骑手离婚，她不能再婚。 He later added a number of riders to this hypothesis. 他后来在这个假设中增加了一些附加条件。
Word Originlate Old English rīdere ‘mounted warrior, knight’ (see ride, -er).