Command key

key on Macintosh computers used in shortcuts for menu options

The Command key, known as the open-Apple key in documentation previous to the Apple Macintosh family of computers, is a modifier key present on Apple Keyboards. An "extended" Macintosh keyboard—the most common type—has two command keys, one on each side of the space bar. Some compact keyboards have one only on the left.
See more at Wikipedia.org...

Noun
1. (computer science) the key on a computer keyboard that is used (in combination with some other key) to type control characters
(synonym) control key
(hypernym) key
(classification) computer science, computing

feature key