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Meaning of semidouble

sem•i•dou•ble

Pronunciation: (sem"ē-dub'ul, sem"ī-), [key]
— adj. Bot.
  1. having more petals than those of a single flower but fewer than those of a double flower.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.