FAMILIARITY
familiarity, impropriety, indecorum, liberty
(noun) an act of undue intimacy
familiarity, intimacy, closeness
(noun) close or warm friendship; “the absence of fences created a mysterious intimacy in which no one knew privacy”
familiarity
(noun) usualness by virtue of being familiar or well known
casualness, familiarity
(noun) a casual manner
acquaintance, familiarity, conversance, conversancy
(noun) personal knowledge or information about someone or something
Source: WordNet® 3.1
Etymology
Noun
familiarity (countable and uncountable, plural familiarities)
The state of being extremely friendly; intimacy.
Undue intimacy; inappropriate informality, impertinence.
An instance of familiar behaviour.
Close or habitual acquaintance with someone or something; understanding or recognition acquired from experience.
Source: Wiktionary
Fa*mil`iar"i*ty, n.; pl. Familiarities. Etym: [OE. familarite, F.
familiaritéfr. L. faniliaritas. See Familiar.]
1. The state of being familiar; intimate and frequent converse, or
association; unconstrained intercourse; freedom from ceremony and
constraint; intimacy; as, to live in remarkable familiarity.
2. Anything said or done by one person to another unceremoniously and
without constraint; esp., in the pl., such actions and words as
propriety and courtesy do not warrant; liberties.
Syn.
– Acquaintance; fellowship; affability; intimacy. See Acquaintance.
Source: Webster’s Unabridged Dictionary 1913 Edition