The phrase "we were acquainted" is grammatically correct and usable in written English.
You could use it to describe the relationship between two people prior to an event. For example, "We were acquainted before the party, but we didn't become friends until later."
Elementarism has sometimes been defended by appealing to something like Russell's principle of acquaintance, understood as the tenet that only things with which we are acquainted should be thought to exist, together with the claim that we are acquainted with first-order properties but not with those of any higher orders.
"We're acquainted with the Under-Secretary.
"It's very odd to see them in our midst, but we're acquainted," Chaibou added.
"We are acquainted with a mere pellicle of the globe on which we live," writes Thoreau, "We know not where we are".
We are acquainted with a woman whose station wagon brakes failed one morning as she was nearing the busiest street on Martha's Vineyard.
But several dozen may be seen at ground level at the 1897 Bowling Green Building at 5-11 Broadway; The Real Estate Record and Guide archly sniffed that it had "more anthemia than any other work with which we are acquainted".
We are acquainted with an interesting and puzzling realm of experience: the realm of the beautiful, the ugly, the sublime, and the elegant; of taste, criticism, and fine art; and of contemplation, sensuous enjoyment, and charm.
In the most recent version, Roman Polanski's "The Pianist," we are acquainted with the fate of an upper-bourgeois family in Warsaw from 1939 to 1945, and particularly with the story of the family's musical son, Wladyslaw (or Wladek) Szpilman, a real-life piano virtuoso and composer who regularly played Chopin on Polish radio.
1. Yet another way to refer to this same basic idea is to speak of objects with which we are acquainted (or, sometimes, directly acquainted).
