- any orchid of the genus Cypripedium, the flowers of which have a protruding petal somewhat resembling a slipper: all species are reduced in numbers, some greatly.
- any of several other related plants having similar flowers, as of the genera Paphiopedilum and Phragmipedium.
- any of various orchids of the Eurasian genus Cypripedium, esp C. calceolus, having reddish or purple flowers