n.病弱；病身
His claim to ownership is invalid. 他的所有权是无效的。
A passport that is out of date is invalid. 护照过期是无效的。
His father is a bed-ridden invalid. 他父亲是个缠绵病榻的人。
He has been an invalid all his life. 他终身残废。
The invalid gained colour under the doctor's care. 病人在医生的治疗下，脸色逐浙红润。
