To enquire means to ask a question or seek information about something. When you enquire about library hours, you're asking when it opens and closes. When a detective enquires into a mystery, she's investigating what happened by asking questions and gathering facts.

The word suggests a somewhat formal or polite way of asking. You might enquire about a friend's health after they've been sick, or enquire at the front desk about where to find a classroom. Scientists enquire into the causes of natural phenomena. A curious student enquires about how things work.

An enquiry (or inquiry) is the act of asking or the question itself: “The principal received several enquiries about the school trip.”