OHabbr.1. Ohio2. open houseoh 1 (?)interj.1. Used to express strong emotion, such as surprise, fear, anger, or pain: Oh?can’t you stop making so much noise?2. Used in direct address: Oh, sir! You forgot your keys.3. Used to indicate understanding or acknowledgment of a statement: Oh, I see. You can’t come until tomorrow.oh 2 (?)n. Zero.[From the number zero’s resemblance to the letter O.]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.oh (??) interjan exclamation expressive of surprise, pain, pleasure, etcsentence connectoran expression used to preface a remark, gain time, etc: oh, I suppose so. OH abbreviation for (Placename) Ohio Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014oh (o?) interj., n., pl. oh’s, ohs, interj. 1. (used as an exclamation of surprise, pain, disapprobation, sympathy, agreement, etc.) 2. (used in direct address to attract the attention of the person spoken to.) n. 3. the exclamation ?oh.? v.i. 4. to utter or exclaim ?oh.? [later sp. of O, from mid-16th century] OH Ohio. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.