bastion

noun

1. A projecting part of a rampart or other fortification.

   “[…] Fort Camosun had swelled herself from being a little Hudson's Bay Fort, inside a stockade with bastions at the corners, into being the little town of Victoria, and the capital of British Columbia.”

2. A well-fortified position; a stronghold or citadel.
3. (figuratively)A person, group, or thing, that strongly defends some principle.

   “a bastion of hope”

   “the bastion of democracy”

4. Any large prominence; something that resembles a bastion in size and form.

   “[…] yonder cloud That rises upward always higher, ⁠And onward drags a labouring breast, ⁠And topples round the dreary west, A looming bastion fringed with fire.”

   “It spread slowly up from the sea-rim, a welling upwards of pure white light, ghosting the beach with silver and drawing the grey bastions of sandstone out of formless space.”

verb

1. (transitive)To furnish with a bastion.