101 UK /ˌwʌnəʊˈwʌn/US /ˌwʌnˌoʊˈwʌn/adjective 1noun 1forms 1 adjective1 •(US, Canada) Of a fact, subject, etc.: basic, beginner-level, elementary.Geology 101 tells us that you can’t build a reservoir on sandstone.My dog flunked out of Crate Training 101. noun1 •(informal) An introduction to a topic; a rundown of its basics.I need you to give me a quick 101 on how you assemble the WIP reports. forms101s