performance or utterance of action or speech: ‘Yes, sir,’ said the girls in unison. ! 2 Music coincidence in pitch of sounds or notes: the flutes play in unison with the violas. state of the unison
Licensed under Public domain via Wikimedia Commons - https://commons.wikimedia.org/wiki/ File:Woman_suffrage_headquarters_Cleveland.jpg#mediaviewer/File:Woman_suffrage_headquarters_Cleveland.jpg 1920 1910s Hans Rosling Ha-Joon Chang Washing Machine Is A More Important Invention Than The Internet