over-familiarity

noun, plural fa·mil·i·ar·i·ties.

1. thorough knowledge or mastery of a thing, subject, etc.
2. the state of being familiar; friendly relationship; close acquaintance; intimacy.
3. an absence of ceremony and formality; informality.
4. freedom of behavior justified only by the closest relationship; undue intimacy.
5. Often familiarities. an instance of such freedom, as in action or speech.
6. a sexual liberty or impropriety.

noun plural -ties

1. reasonable knowledge or acquaintance, as with a subject or place
2. close acquaintanceship or intimacy
3. undue intimacy
4. (sometimes plural) an instance of unwarranted intimacy

n.c.1200, from Old French familiarite and directly from Latin familiaritatem (nominative familiaritas) “intimacy, friendship,” from familiaris “friendly, intimate” (see familiar). Meaning “undue intimacy” is from late 14c. That of “close acquaintance” is from c.1600.