fortification agate
Webster's Dictionary (GCIDE)
Fortification \For`ti*fi*ca"tion\, n. [L. fortificatio : cf. F. fortification.]
1.The act of fortifying; the art or science of fortifying places in order to defend them against an enemy. [1913 Webster]
2.That which fortifies; especially, a work or works erected to defend a place against attack; a fortified place; a fortress; a fort; a castle. [1913 Webster]
Fortification agate, Scotch pebble.
Syn: Fortress; citadel; bulwark. See Fortress. [1913 Webster]