Pronunciation: The first syllables of the two words sound like `will’ and `nil’ respectively. The final `y’ in both cases is pronounced like the `i’ in `bit’ and `sit’. The main stress is on `nil’.
When you do something `willy-nilly’, you do it under compulsion. You do it whether you like it or not; you don’t really have a choice regarding the matter.
Example: Be careful. Otherwise, you will be dragged, willy-nilly, into the fight.
The expression can also be used to mean doing something in a careless or disorganised manner; doing it without any prior planning.
Example: The students rushed in and threw their bags willy-nilly into the storeroom.
The expression is a contraction of `will ye, nill ye’. `Nill’, a word that we no longer use, meant `to be unwilling’.