cit·ron (s?t?r?n)n.1. a. A thorny evergreen shrub or small tree (Citrus medica) native to India and widely cultivated for its large lemonlike fruits that have a thick warty rind.b. The fruit of this plant, whose rind is often candied and used in confections and fruitcakes.2. A globose watermelon (Citrullus lanatus var. citroides) having white flesh that is candied or pickled.3. A grayish-green yellow.[Middle English, from Old French, alteration (influenced by limon, lemon) of Latin (m?lum) citreum, citron (fruit), from citrus, citron tree.]cit?ron adj.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.citron (?s?tr?n) n1. (Plants) a small Asian rutaceous tree, Citrus medica, having lemon-like fruit with a thick aromatic rind. See also citron wood2. (Plants) the fruit of this tree3. (Plants) Also called: citron melon a variety of watermelon, Citrullus vulgaris citroides, that has an inedible fruit with a hard rind4. (Cookery) the rind of either of these fruits, candied and used for decoration and flavouring of foods5. (Colours) a greenish-yellow colour[C16: from Old French, from Old Provençal, from Latin citrus citrus tree]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014cit?ron (?s? tr?n) n. 1. a pale yellow fruit resembling the lemon but larger and with thicker rind borne by a small tree, Citrus medica, allied to the lemon and lime. 2. the tree itself. 3. the rind of the fruit candied and preserved. 4. citron melon. [1375?1425; late Middle English