chumminess vs sociability

chumminess and sociability both are nouns.

Word	Noun	Adjective	Verb	Adverb
chumminess	Yes	No	No	No
sociability	Yes	No	No	No

As nouns, sociability is a hypernym of chumminess; that is, sociability is a word with a broader meaning than chumminess:

chumminess: the quality of affording easy familiarity and sociability
sociability: the relative tendency or disposition to be sociable or associate with one's fellows

Other hypernyms of chumminess include sociableness.

chumminess (noun)	sociability (noun)
the quality of affording easy familiarity and sociability	the relative tendency or disposition to be sociable or associate with one's fellows