1. An addition that extends a main building
   "The school built an annex to accommodate the growing number of students";
   - annexe [Brit], extension, wing

1. Take (territory) as if by conquest
   "Hitler annexed Lithuania"
    
2. Add an extra part to
   "The city annexed the neighbouring town"

Derived forms: annexing, annexes, annexed

Type of: add on, addition, add-on, affix, append, arrogate, assume, improver, seize, supplement, take over, usurp

Part of: building, edifice

Encyclopedia: Annex, Oregon