The instructions for this task are ill-defined.

He made a decision based on ill-informed opinions.

His ill-considered decision led to disastrous consequences.

Never speak ill of others.

The detective was assigned to investigate the house of ill repute in the city's red-light district.

Engaging in illegal activities can result in severe consequences.

This book contains beautiful illustrations.

This diagram will illustrate the process of photosynthesis.

His explanation for his actions was completely illogical.

Don't be fooled by the illusion of success.