wallflower

noun

1. Any of several short-lived herbs or shrubs of the Erysimum genus with bright yellow to red flowers.

   “A polypetalous corolla is either cruciform, as in a wall-flower, rosaceous, papilionaceous, as in the pea kind, or incomplete, when some parts found in analogous flowers are wanting.”

2. Gastrolobium grandiflorum, a poisonous bushy shrub, endemic to Australia.
3. A person who does not dance at a party, due to shyness or unpopularity; by extension, anyone who is left on the sidelines while an activity takes place.

   “Mrs. Galbraith shook all over with laughter as she replied, "Hear that boy, asking me to dance ! I'm content to be a wallflower, now-a-days."”

   “And now, by virtue of his office, he is entitled to a seat in the Grand Lodge. Is it any wonder he is a wall-flower there […]”

   “It is a triumph, of course, to have plenty of partners, and not to be a wallflower for a single dance.”

   “Jack Breen was a wallflower; still at the same time I noticed he was cultivating an ornamental smile — a Jack of Trumps, you bet.”

   “She was a wallflower in a sleepy little town itself a wallflower. She was a joke to the village wits and a byword to the village belles.”

4. (informal)Any person who is socially awkward, shy, or reserved.

   “I've always been a wallflower, even in my own home. But, I'm willing to learn to be a part of your world. I would like to. I have already told my parents that I want to go to soirées.”

verb

1. (intransitive)To stand shyly apart from a dance, waiting to be asked to join in.

   “[…] the idea that a full tango experience is impossible without the presence of wallflowers and without the threat of wallflowering as the potential dancers enter the tango club.”