Definition of "ailment"

He had always been remarkably immune from such little ailments, and had only once in his life been ill, of a vicious pneumonia long ago at school. He hadn't the faintest idea what to with a cold in the head, he just took quinine and continued to blow his nose.

1922, Michael Arlen, “2/9/1”, in “Piracy”: A Romantic Chronicle of These Days‎