(education) high school; senior high school

to be acquainted with each other

being acquainted with each other / acquaintance

age, era, period (of time) / the times, spirit of the age / antiquity / a time in one's life, one's days (in college etc.)

(chiefly women's speech) first person singular pronoun: I, me

private; mine

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

a personal or private matter / (by extension) selfishness

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

personal, private / secret