- Tis is defined as a shortened version of saying it is.
An example of tis is the line in the song "Deck the Halls" about it being the season to be jolly.
'tis definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
Old Poet. it is
'tis definition by American Heritage Dictionary
Contraction of it is.