T-shirt also tee shirt (t??shûrt?)n. A short-sleeved, pullover shirt with no collar.[Perhaps from its being shaped like the letter T, when spread out.]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.T-shirt , tee shirt or tee-shirtn (Clothing & Fashion) a lightweight simple garment for the upper body, usually short-sleeved[so called because of its shape]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014T-shirt or tee shirt (?ti???rt) n. a lightweight, usu. knitted, pullover shirt, typically with short sleeves and a collarless round neckline, worn as an undershirt or outer garment. Also called tee . [1915?20, Amer.; alluding to its shape when spread out flat] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.