adj.无效的；病弱的
n.病人；残疾者
vt.退役；遣送回家
A passport that is out of date is invalid. 护照过期是无效的。
Unless a check is signed, it is invalid. 支票除非签了名，否则是无效的。
She looks after her invalid mother. 她照看病弱的母亲。
用作名词 (n.)Nobody looks after the invalid. 没人照顾这个病人。
He never fully recovered, and had to spend the rest of his life as an invalid. 他没能完全康复，于是不得不成了一名残疾者度过余生。
用作及物动词 (vt.)He was invalided out of the army because of the wounds he received. 他因负伤而退役。
Ambassador decided that he must invalid his sick radio-officer home. 大使决定把患病的无线电报员遣送回国。
