(inorganic chemistry, archaic) Nitric acid. / (alchemy) A corrosive liquor made of saltpeter, serving as a solvent for dissolving silver and all other metals except gold.

The area of the earth between 40 and 50 degrees south, prone to gale-force westerly winds.

plural of back forty

plural of north forty

(phonetics) Immediately preceding a fortis consonant.

plural of pianny forty

plural of pianny-forty

(set theory) The paradox that supposing the existence of a set of all ordinal numbers leads to a contradiction; construed as meaning that it is not a properly defined set.

Cardinal number after forty-four and before forty-six.

(firearms) A .45-caliber firearm.