present participle of do ill.

Britain standard spelling of ill-humored.

(mathematics) Not well-posed.

Poorly received; not enjoying the positive reception expected.

(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

Unsubstantiated, not based on fact or evidence.

Alternative form of ill behaved

(obsolete) The disease coenurosis in sheep.

Bad luck; misfortune