1. any of various plants, esp. of the genera Ipomoea and Convolvulus, as I. purpurea, a twining plant having cordate leaves and funnel-shaped flowers of various colors, often opening only in the morning.
2. a racehorse that runs faster in morning workouts than in afternoon races. Also,morn'ing-glo"ry.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.