ill
UK[ɪl]US[ɪl]
adj
Not in good health; sick or unwell
adj
Bad or harmful
adv
Badly, wrongly, or in an unsatisfactory way
n
A problem or misfortune
Etymology
The word 'ill' entered English from Old Norse 'illr', meaning 'bad, evil, or difficult'. It supplanted the native Old English word 'yfel' (evil) in many of its adjectival senses related to poor quality or misfortune. Its path into general use for describing poor health or sickness is a semantic narrowing from the broader concept of 'badness'. This compact, potent root has remained stable in form and core meaning for centuries, directly connecting the ancient concept of 'bad' to modern conditions of sickness, harm, and poor performance.
Analysis
This is a simplex word of Old Norse origin. It functions as a complete, unanalyzable root in modern English.
Examples
He has been ill with the flu for a week.
The company suffered no ill effects from the economic shift.
She could ill afford to lose her job at that time.