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.
Literature
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. ISBN0-89659-774-1.
Leyi Li: “Tracing the Roots of Chinese Characters: 500 Cases”. Beijing 1993, ISBN978-7-5619-0204-2
GF 0011-2009 Table of Indexing Chinese Character Components prescribes 201 principle indexing components and 100 associated indexing components (in brackets) used in Simplified Chinese. Not all associated indexing components are listed above.