From Longman Dictionary of Contemporary Englishwallflowerwall‧flow‧er /ˈwɔːlˌflaʊə $ ˈwɒːlˌflaʊər/ noun [countable] 1 informalDL someone at a party, dance etc who is not asked to dance or take part in the activities2 HBPa sweet-smelling garden plant with yellow and red flowers
Examples from the Corpus
wallflower• Hey, there are even pastels like peach and lilac this season, so nobody has to be a wallflower.• The worst of fates was to be a wallflower passed over and rejected.• Sometimes, Joan was the dowdy, make-up-less wallflower with curves that looked more like sacks.• In fact you could say that I was a real wallflower.• Beyond that, she had shown that women were capable of being more than simpering wallflowers, or unpaid housekeepers.• They looked a little out of it, the wallflowers at the party.• It was cool and fresh in the summer, the back yard blooming with wallflowers and purple bells.From Longman Business Dictionarywallflowerwall‧flow‧er /ˈwɔːlˌflaʊəˈwɒːlˌflaʊər/ noun [countable] journalismFINANCE an investment that is not popular with investors because it is not profitable enoughInvestors started buying the new issue in large numbers, turning a Wall Street wallflower into one of the hottest financial products. 