Glossary
Anchor
In one line: The defender who stays on a site and holds it until help arrives.
What it means
The anchor is the defender who stays on their site even when the action is elsewhere. Their job is not to rack up kills but to make sure the site never falls silently: see who comes in, call it, and waste the attackers' time while teammates rotate.
A good anchor often plays spots they can fall back from, uses utility to delay, and does not die alone out of pride. On many teams the anchor is a sentinel with traps, but anyone with patience and discipline can do it.
An example
On Ascent you are holding B alone. You hear three sets of footsteps and a flash: instead of taking on all three, you call "three B, flash", fire once from the back and fall back towards the retake. You just bought precious seconds for the teammates coming from mid.