ill: [12] ‘Sick’ is not the original meaning of ill. To start with it meant ‘bad’ (a sense which survives, of course, in contexts such as ‘ill-will’, ‘illmannered’, etc), and ‘sick’ did not come on the scene until the 15th century. The word was borrowed from Old Norse illr, which is something of a mystery: it has other modern descendants in Swedish illa and Danish ilde ‘badly’, but its other relations are highly dubious (Irish olc has been compared) and no one knows where it originally came from. The sense ‘sick’ was probably inspired by an impersonal usage in Old Norse which meant literally ‘it is bad to me’. => like[ill etymology, ill origin, 英语词源]