cheese·steak (ch?z?st?k?)n. A sandwich consisting of a long roll filled with thinly sliced grilled beef, cheese, and often grilled onions.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.cheesesteak (?t?i?z?ste?k) na sandwich filled with grilled beef and cheeseCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014