Resounding describes something obvious or unambiguous. If it's clear that every single guest had a wonderful time, you can call your party a resounding success.
Use this adjective to emphasize how great (or terrible) something is, like your best friend's resounding victory in the student council election, or the resounding disaster of your plan to carpet your bedroom using moss. It's also useful for describing a sound that echoes or reverberates: "The resounding slam of her bedroom door told me my sister was really angry." The Latin root means "echo."