bastion

noun

1. Fortification. a projecting portion of a rampart or fortification that forms an irregular pentagon attached at the base to the main work.
2. a fortified place.
3. anything seen as preserving or protecting some quality, condition, etc.: a bastion of solitude; a bastion of democracy.

noun

1. a projecting work in a fortification designed to permit fire to the flanks along the face of the wall
2. any fortified place
3. a thing or person regarded as upholding or defending an attitude, principle, etcthe last bastion of opposition

n.

1560s, from Middle French bastillon, diminutive of Old French bastille “fortress, tower, fortified, building,” from Old Provençal bastir “build,” perhaps originally “make with bast” (see baste (v.1)).