TUNNEL n.
A level passage driven across the measures, or at right angles to veins which it is desired to reach; -- distinguished from the drift, or gangway, which is led along the vein when reached by the tunnel. Tunnel head (Metal.), the top of a smelting furnace where the materials are put in. -- Tunnel kiln, a limekiln in wh…
UN- n.
o almost any adjective, or participle used adjectively, or adverb, from which it may be desired to form a corresponding negative adjective or adverb, and is also, but less freely, prefixed to nouns. Un- sometimes has merely an intensive force; as in unmerciless, unremorseless. I.