1. a warning in advance of future action or a limiting or modifying condition attached to something
add a caveat/attach a caveat/just one caveat
A 'caveat' can be a warning to consider before deciding on future actions: "One caveat: while the photo shoot is free, the photos remain the property of the photographer and can be modified and reproduced in any way." Or it can be a condition of an agreement: "The client has agreed to give us an extension with the caveat that they can hire additional providers to speed up the process." This term is often used in terms and conditions or in legal agreements. It is a formal word used almost exclusively in professional and legal contexts. Similar terms include 'the catch is', or 'the terms are'.