any plant belonging to the genus Antirrhinum, of the figwort family, esp. A. majus, cultivated for its spikes of showy flowers, each having a corolla supposed to resemble the mouth of a dragon.
snap·drag·on (snāp'drāg'ən) n. Any of several plants of the genus Antirrhinum, especially the widely cultivated Mediterranean herb A. majus, having showy racemes of two-lipped, variously colored flowers.
[From the imagined resemblance of the flowers to the mouth of a dragon.]