go against, as of rules and laws
an open clash between two opposing groups (or individuals)
a hostile meeting of opposing military forces in the course of a war
a disagreement or argument about something important
an incompatibility of dates or events
a state of opposition between persons or ideas or interests
be in conflict
opposition between two simultaneous but incompatible feelings
opposition in a work of drama or fiction between characters or forces (especially an opposition that motivates the development of the plot)
be of different opinions
be different