n. [ OF. aketon, auqueton, F. hoqueton, a quilted jacket, fr. Sp. alcoton, algodon, cotton. Cf. Cotton. ] A stuffed jacket worn under the mail, or (later) a jacket plated with mail. [ Spelled also hacqueton. ] [ Obs. ] Halliwell. Sir W. Scott. [ 1913 Webster ]

n. (Chem.) One of a series of organic compounds, being cyclic esters which may be regarded as anhydrides of certain hydroxy acids. In general, they are colorless liquids, having a weak aromatic odor. They are so called because the typical lactone is derived from lactic acid. [ 1913 Webster ]

a. [ From Lactone. ] (Chem.) Of, pertaining to, or derived from, a lactone. [ 1913 Webster ]

a. [ From Lactose. ] (Chem.) Pertaining to, or designating, an acid obtained by the oxidation of milk sugar (lactose). [ 1913 Webster ]