Radical 17 or radical open box (凵部) is one of 23 of the 214 Kangxi radicals that are composed of 2 strokes.

凵 is also the 20th indexing component in the Table of Indexing Chinese Character Components predominantly adopted by Simplified Chinese dictionaries published in mainland China.

As for the similar radicals 22 匚 and 13 冂, the name of radical 17 is purely descriptive of its shape, 下三框 "lower three-sided frame".

• Oracle bone script character
• Large seal script character
• Small seal script character

The radical does not occur as a character on its own. In combination, it historically takes meanings such as "open mouth", "box", "frame", "hole" or "receptacle".

Also derived from the radical are the Simplified Chinese characters including 击 "to hit", without any historical connection to the radical.

幽 "deep, dark" is derived from radical 46 (山 "mountain") rather than radical 17.

• Fazzioli, Edoardo (1987). Chinese calligraphy : from pictograph to ideogram : the history of 214 essential Chinese/Japanese characters. calligraphy by Rebecca Hon Ko. New York: Abbeville Press. ISBN 0-89659-774-1.
• Leyi Li: “Tracing the Roots of Chinese Characters: 500 Cases”. Beijing 1993, ISBN 978-7-5619-0204-2
• KangXi: page 134, character 17

Wikimedia Commons has media related to Radical 017.

• Unihan Database - U+51F5