When you instil a feeling, a habit, or a way of thinking in someone, you put it in slowly, over a long time — not with one talk. Parents try to instil honesty. A coach tries to instil confidence. A harsh classroom can instil fear. The picture behind the word is a drop at a time: the idea goes in little by little until it sits inside the person. British English writes instil; American English writes instill, with two l's. It is a somewhat formal word. You meet it in talk about raising children, school, and leadership. You do not instil a fact you said once; that is just telling. Instil is the slow kind. Doctors also instil drops into an eye — the same “drop by drop” idea, used of liquid.