'ill-worded' originates from English, specifically from the combination of the adjective 'ill' (from Old English 'yfel') meaning 'bad' and the participial/adjectival use of 'word' (Old English 'word') meaning 'speech' or 'utterance', with the past-participial suffix '-ed' forming 'worded'.

'ill-worded' changed from earlier English compound usage such as 'ill worded' (two words) and was later commonly written with a hyphen as 'ill-worded'; the element 'worded' developed from the noun 'word' used in a past-participial/adjectival sense.

Initially it meant 'badly expressed' and over time it has retained that core meaning of 'poorly or inappropriately phrased'.