(chemistry) Any polyunsaturated fatty acid having a double bond between the third and fourth carbon atoms from the end of the molecule farthest from the carboxylic acid; they are found in green vegetables and in the oils of fish such as salmon and mackerel; they are essential fatty acids, and seem to be beneficial in reducing the risk of heart disease.

A tool used in machining fields, especially milling, to aid in setup. It is a block of steel that is precisely squared and parallel whose sides are 1, 2, and 3 inches long, respectively. May contain arranged holes. Similar, larger blocks are called 2-4-6 blocks.

plural of 1-2-3 block

plural of omega-3 fatty acid

plural of ω-3 fatty acid

Abbreviation of omega-3 fatty acid.

plural of 501(c)(3)

A gramophone record played at 33⅓ revolutions per minute.

Abbreviation of three-dimensional. / Obsolete form of 3rd.

thruppence, threepence, a coin valuing three pennies