wallflower
noun [ C ] uk/ˈwɔːəlflaʊər/ us/ˈwɑːlˌflaʊ.ɚ/
(PLANT)
桂竹香，墙头花
a pleasant smelling garden plant that has yellow, orange, or brown flowers that grow in groups
(SHY PERSON)
informal壁花;（尤指社交活动中）无人青睐的害羞女子
a shy person, especially a girl or woman, who is frightened to involve herself in social activities and does not attract much interest or attention
Sooner or later someone would take pity on the poor wallflower and ask her to dance. 迟早会有人可怜那个没有舞伴的害羞姑娘，请她跳舞的。