us versus them

Etymology
us + versus + them

Noun

 * 1) A state of opposition between two groups, mostly based on group membership.
 * 2) * 1968, "Annual Representative Meeting, Eastbourne, 1968", British Medical Journal Supplement, (7/6/1968), pp. 1–36. p. 24
 * The inevitable result of disenfranchisement was that the disinterested would become even more disinterested; the schism “us” versus “them” would grow; and special groups&mdash;e.g., women members&mdash;would feel that they were inadequately represented.
 * 1) * 1983, M. Stanley Whitley, "Hopefully: A Shibboleth in the English Adverb System", American Speech, (58) 2 (Summer 1983), pp. 126–49. p. 132
 * From this social perception follows the corollary us-versus-them argument. Anyone who learns that this marker of identity “offends the ear” joins the select group of those in the know, and will have a criterion by which he can both identify and judge the out-group who “desire to be up with the latest in thing,” and reassert his own membership in the club of those with taste.
 * From this social perception follows the corollary us-versus-them argument. Anyone who learns that this marker of identity “offends the ear” joins the select group of those in the know, and will have a criterion by which he can both identify and judge the out-group who “desire to be up with the latest in thing,” and reassert his own membership in the club of those with taste.

Usage notes
Commonly used as an appositive: We must rise above us versus them thinking.