Flint age. (Geol.) Same as Stone age, under Stone. -- Flint brick, a fire made principially of powdered silex. -- Flint glass. See in the Vocabulary. -- Flint implements (Archæol.), tools, etc., employed by men before the use of metals, such as axes, arrows, spears, knives, wedges, etc., which were commonly made of flint, but also of granite, jade, jasper, and other hard stones. -- Flint mill. (a) (Pottery) A mill in which flints are ground. (b) (Mining) An obsolete appliance for lighting the miner at his work, in which flints on a revolving wheel were made to produce a shower of sparks, which gave light, but did not inflame the fire damp. Knight. -- Flint stone, a hard, siliceous stone; a flint. -- Flint wall, a kind of wall, common in England, on the face of which are exposed the black surfaces of broken flints set in the mortar, with quions of masonry. -- Liquor of flints, a solution of silica, or flints, in potash. -- To skin a flint, to be capable of, or guilty of, any expedient or any meanness for making money. [Colloq.]