Woodworking Glossary
Flush

HABS / Library of Congress, Public domain, via Wikimedia Commons
Flush describes two surfaces meeting at exactly the same level, with no step or gap between them -- a plug sanded flush with the surrounding wood, a drawer front flush with the cabinet face. "Flush-trim" bits and cuts are named for exactly this: trimming one material down until it's perfectly level with another, guided by a bearing riding along the reference surface.
Images
Product: A built-in bookshelf with flush trim, from a Historic American Buildings Survey record — HABS / Library of Congress, Public domain, via Wikimedia Commons

