A four-sided plane figure with four right angles.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "rectangle" in a sentence
"All you need to have on hand before arranging your favorite flavor of cupcakes into a large rectangle is red, white and blue frosting (or sprinkles)."
"If we learn two things, it's that that Scott-Jean-Logan-Emma lust love rectangle is a little icky."
"I found one that looks plausible – a square of lace, attached to the neck at one corner, with a plain rectangle underneath, both edged with the same pretty little edging."