(pathology) An illness that is normally incurable and that a terminally ill person would not be expected to recover from.

(idiomatic) To harm, to injure.

present participle of do ill.

simple past tense of do ill.

Third-person singular simple present indicative form of do ill

Britain standard spelling of ill-humored.

(mathematics) Not well-posed.

(insurance) Insurance that pays out a lump sum benefit on the diagnosis of a serious (life-threatening) illness in the life assured within the term of the policy, and nothing on death or healthy survival to the end of the term.

(dated) poor or unfortunate; not well off

Poorly received; not enjoying the positive reception expected.