lych·nis (l?k?n?s)n. Any of various plants of the genus Lychnis of the pink family, including cultivated species such as the rose campion.[New Latin Lychnis, genus name, from Latin lychnis, a red flower, from Greek lukhnis; akin to lukhnos, lamp; see leuk- 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.lychnis (?l?kn?s) n (Plants) any caryophyllaceous plant of the genus Lychnis, having red, pink, or white five-petalled flowers. See also ragged robin[C17: New Latin, via Latin, from Greek lukhnis a red flower; related to lukhnos lamp]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014lych?nis (?l?k n?s) n. any showy-flowered plant of the genus Lychnis, of the pink family. [1595?1605;