Synonyms and related words :
ailing, at a discount, at a reduction, bad, below, below deck, below standard, below the mark, belowstairs, critically ill, down, down below, downstairs, faint, faintish, feeling awful, feeling faint, feeling something terrible, ill, in danger, indisposed, infra, laid low, mortally ill, not quite right, off, off-color, out of sorts, rocky, seedy, sick, sick unto death, sickish, substandard, taken ill, under, under the weather, underfoot, unwell