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1. Any of various plants that move or are believed to move in response to the sun, especially the Mediterranean species Chrozophora tinctoria.
2. See heliotrope.
[Middle English turnesole, dye made from C. tinctoria, from Old French tournesol, from Old Italian tornasole : tornare, to turn (from Latin tornāre; see turn) + sole, sun (from Latin sōl; see sāwel- in Indo-European roots).]
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.
1. (Plants) any of various plants having flowers that are said to turn towards the sun
2. (Plants) a euphorbiaceous plant, Croton tinctoria, of the Mediterranean region that yields a purple dye
3. (Dyeing) the dye extracted from this plant
[C14: from Old French tournesole, from Old Italian tornasole, from tornare to turn + sole sun, from Latin sōl sun]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
1. any of several plants regarded as turning with the movement of the sun.
2. a European plant, Chrozophora tinctoria, of the spurge family, yielding a purple dye.
3. the dye itself; litmus.
[1325–75; Middle English turnesole < Middle French tournesol < Italian tornasole, literally, (it) turns (toward the) sun, on the model of Greek hēliotrópion heliotrope]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.