ill / il/ • adj. 1. not in full health; sick: her daughter is seriously ill | a terminally ill patient. 2. poor in quality: ill judgment dogs the unsuccessful. ∎ harmful: she had a cup of the same wine and suffered no ill effects. ∎ hostile: I bear you no ill will. ∎ (esp. of fortune) not favorable: no one less deserved such ill fortune than McStay. • adv. 1. [usu. in comb.] badly, wrongly, or imperfectly: some of his premises seem ill-chosen it ill becomes one so beautiful to be gloomy. ∎ unfavorably or unpropitiously: something which boded ill for unwary golfers. 2. only with difficulty; hardly: she could ill afford the cost of new curtains. • n. 1. [as pl. n.] (the ill) people who are ill: a day center for the mentally ill. 2. (usu. ills) a problem or misfortune: a lengthy work on the ills of society. ∎ evil; harm: how could I wish him ill? PHRASES: ill at ease uncomfortable or embarrassed. speak (or think) ill of say (or think) something critical about.