Homophily
Etymology
From Greek "homos" ("same") and "philia" ("love, affection"). The compound entered sociology through Paul Lazarsfeld and Robert K. Merton in 1954, who set it against its opposite, heterophily. Flagged as a mid-century scholarly coinage from Greek roots.
noun · /hoh-MOF-ih-lee/
The tendency to form ties with people who are similar to oneself.
What it names
The technical name for "birds of a feather flock together," useful for diagnosing why networks segregate and echo chambers form.
Example
Dating apps promise variety but their algorithms often deepen homophily, quietly steering users toward people just like them.
Related idea
Compare echo chamber, an outcome; homophily is the underlying social pull that helps produce it.