mother ship

Short definition from Wiktionary

Noun

1. 1
   A vessel, aircraft or spacecraft that serves or carries a smaller vessel or vessels that operate independently from it.
2. 2
   The main source or supporter of something.
3. 3
   The largest vessel, especially a spaceship, in a fleet, from which the fleet is commanded; a flagship.
4. 4
   The largest and most fearsome example of something.