invalid

お気に入りの作家John Grishamの作品をまた読むことにしました。図書館から本を受け取って分かったのですが、Ford Countyの題がついていましたが、中身は７つの短編になっていました。最初に読むのはBlood Driveと題された話です。今日とりあげるのは馴染みのある単語 "invalid" です。
By the time the news of Bailey's accident spread through the rule settlement of Box Hill, there were several versions of how it happened. Someone from the construction company called his mother that he had been injured when some scaffolding collapsed at a building site in downtown Memphis, that he was undergoing surgery, was stable, and was expected to survive. His mother, an invalid, weighed over 400 pounds and was known to be excitable, missed some of the facts as she began to scream and carry on.
"invalid" の意味としては無効、無能、不能を直ぐに思い浮かべますが、上の文での意味としてはちょっと合いません。 早速辞書を引きます。
・Oxford English Dictionary: A person made weak or disabled by illness or injury: [as modifier]: an invalid husband
・Cambridge English Dictionary: someone who is sick and unable to take care of himself or herself, especially for a long time: Is the invalid in bed?
・Vocabulary.com: A person who is very sick or injured and needs frequent care is an invalid. Also, something no longer current or useful is invalid.
The main uses of this word have to do with people and things that don't work very well anymore. A driver's license that has expired is invalid -- it needs to be renewed. If you lost your health insurance, it's invalid. People who are called invalids are disabled or incapacitated severely. Be careful with this word, because some think it is inappropriate, since it sounds as if some people are not as valid as others based on physical capability.
なるほど、日本語の無能、不能は否定的なニュアンスが強いのでやたらの人について、少なくとも本人に直接にはつかいませんが、"invalid" も人に対して使う場合は注意が必要ですね。