strong ‧ hold /ˈstrɒŋhəʊld $ ˈstrɒːŋhoʊld/ BrE AmE noun [countable]
1 . an area where there is a lot of support for a particular way of life, political party etc:
The area is a Republican stronghold.
2 . an area that is strongly defended by a military group:
The fighters moved south to their mountain stronghold.
3 . an area where there are large numbers of a rare animal:
one of the last strongholds of the European wolf