The Jargon File (version 4.4.7, 29 Dec 2003):

feature key
 n.

    [common] The Macintosh key with the cloverleaf graphic on its keytop;
    sometimes referred to as flower, pretzel, clover, propeller, beanie (an
    apparent reference to the major feature of a propeller beanie), splat,
    open-apple or (officially, in Mac documentation) the command key. In
    French, the term papillon (butterfly) has been reported. The proliferation
    of terms for this creature may illustrate one subtle peril of iconic
    interfaces.

    Many people have been mystified by the cloverleaf-like symbol that appears
    on the feature key. Its oldest name is ?cross of St. Hannes?, but it occurs
    in pre-Christian Viking art as a decorative motif. Throughout Scandinavia
    today the road agencies use it to mark sites of historical interest. Apple
    picked up the symbol from an early Mac developer who happened to be
    Swedish. Apple documentation gives the translation ?interesting feature?!

    There is some dispute as to the proper (Swedish) name of this symbol. It
    technically stands for the word sev?rdhet (thing worth seeing); many of
    these are old churches. Some Swedes report as an idiom for the sign the
    word kyrka, cognate to English ?church? and pronounced (roughly) /chur'ka/
    in modern Swedish. Others say this is nonsense. Other idioms reported for
    the sign are runa (rune) or runsten /roon'stn/ (runestone), derived from
    the fact that many of the interesting features are Viking rune-stones. The
    term fornminne /foorn'min'@/ (relic of antiquity, ancient monument) is also
    reported, especially among those who think that the Mac itself is a relic
    of antiquity.


The Free On-line Dictionary of Computing (30 December 2018):

feature key
beanie key
clover key
command key
flower key
kyrka
pretzel key
propeller key

    (Or "flower", "pretzel", "clover", "propeller",
   "beanie" (from propeller beanie), splat, "command key") The
   Macintosh modifier key with the four-leaf clover graphic
   on its keytop.

   The feature key is the Mac's equivalent of a control key
   (and so labelled on some Mac II keyboards).  The proliferation
   of terms for this creature may illustrate one subtle peril of
   iconic interfaces.  Macs also have an "Option" modifier key,
   equivalent to Alt.

   The cloverleaf-like symbol's oldest name is "cross of
   St. Hannes", but it occurs in pre-Christian Viking art as a
   decorative motif.  In Scandinavia it marks sites of historical
   interest.  An early Macintosh developer who happened to be
   Swedish introduced it to Apple.  Apple documentation gives the
   translation "interesting feature".

   The symbol has a Unicode character called "PLACE OF INTEREST
   SIGN" (U+2318), previously known as "command key".

   The Swedish name of this symbol stands for the word
   "sev"ardhet" (interesting feature), many of which are old
   churches.  Some Swedes report as an idiom for it the word
   "kyrka", cognate to English "church" and Scots-dialect "kirk"
   but pronounced /shir'k*/ in modern Swedish.  Others say this
   is nonsense.

   (http://fileformat.info/info/unicode/char/2318/index.htm).

   [Jargon File]

   (2005-09-15)