watershed noun uk /ˈwɔː.tə.ʃed/ us /ˈwɑː.t̬ɚ.ʃed/ [ S ] an event or period that is important because it represents a big change in how people do or think about something Kenneth, an omega, is an average highschool senior. Friends, partying, few hooks up here and there, life is pretty simple for him without any future plan. After discovering his pregnancy, life isn't same as before with parents who are not supporting him.