noun

lacking bodily or muscular strength or vitality

Hence The juice or fluid the presence of which in anything is characteristic of a healthy, fresh, or vigorous condition; blood, A quarryman's name for rock which is partially decayed and which exhibits this quality by iron stains and other discolorations. It is usually thrown away, The juice of plants of any kind, especially the ascending and descending juices or circulating fluid essential to nutrition, intransitive verb_ To undermine the foundations of (a fortification), To dig a sap, To proceed by mining, or by secretly undermining; to execute saps, transitive verb_ To subvert by digging or wearing away; to mine; to undermine; to destroy the foundation of, To make unstable or infirm; to unsettle; to weaken, military To pierce with saps, verb_ To make unstable or infirm; to unsettle; to weaken

A person who is weak and infirm; one who is disabled for active service; especially, one in chronic ill health who is unable to care for himself, Any person with a disability, verb_ force to retire, remove from active duty, as of firemen, injure permanently, transitive verb_ To make or render invalid or infirm, To classify or enroll as an invalid, someone who is incapacitated by a chronic illness or injury, One who is confined to home or bed because of illness, disability or injury