anchor
[ ang-ker ]
noun
any of various devices dropped by a chain, cable, or rope to the bottom of a body of water for preventing or restricting the motion of a vessel or other floating object, typically having broad, hooklike arms that bury themselves in the bottom to provide a firm hold.
any similar device for holding fast or checking motion: an anchor of stones.
verb (used with object)
to hold fast by an anchor.
to fix or fasten; affix firmly: The button was anchored to the cloth with heavy thread.
verb (used without object)
to drop anchor; lie or ride at anchor: The ship anchored at dawn.
to keep hold or be firmly fixed: The insect anchored fast to its prey.

The assumption would be the "Anchor" is the person awaiting your arrival. They have stopped the "ship" or in the case the group to await something, IE someone new joining.