a personal or private matter / (by extension) selfishness

personal, private / secret

a personal or private matter / selfishness / privacy, secrecy / (women's speech, obsolete) a brother-in-law

private; mine

(formal) first-person singular pronoun: I, me

a summit (gathering of leaders)

importance

necessity (quality or state of being necessary, unavoidable, or absolutely requisite)

unnecessary

needlessness