incongruous

/ɪŋˈkɔŋgruəs/

Something that's incongruous is inconsistent or incompatible with something else. Remember that Sesame Street song "One of these things is not like the other"? They were talking about that one thing being incongruous.

If we break it down into its Latin roots, incongruous is formed by adding in, meaning “not," to congruous, which means “suitable, proper.” So, something that is incongruous is "not suitable or proper" — in other words, not in harmony with everything else. That's why burping at the dinner table could be called incongruous behavior: it's not proper and certainly doesn't go well with the main course.

Definitions of incongruous

1. adjective

   lacking in harmony or compatibility or appropriateness
   “a plan incongruous with reason”

   “incongruous behavior”

   “a joke that was incongruous with polite conversation”

   synonyms:

   discrepant, inconsistent

   not in agreement

   inappropriate, incompatible, out of keeping, unfitting

   not in keeping with what is correct or proper

   inharmonious

   lacking in harmony of parts

   ironic, ironical

   characterized by often poignant difference or incongruity between what is expected and what actually is

   antonyms:

   congruous

   corresponding in character or kind

   appropriate

   suitable for a particular person, place, condition, etc.

   harmonious

   suitable and fitting