Congruity is a quality of agreement and appropriateness. When there's congruity, things fit together in a way that makes sense. If a team has congruity, the players work together well, even if they don’t win.
The word congruity is from the Old French congruité for "relevance and appropriateness." Students reading quietly in a library is an example of congruity. A clown juggling fire in a library would be an incongruity, which is when things don't fit together. A well-decorated room, where the colors complement each other, has congruity. Wearing a tuxedo to a classical music concert shows congruity: wearing a tux to a heavy metal concert would not.