purple

purple originally, a crimson dye obtained from some molluscs, formerly used for fabric worn by an emperor or senior magistrate in ancient Rome or Byzantium; in figurative use, imperial, royal. In later use, purple came to be used for a colour intermediate between red and blue.

Purple as a colour has symbolic connotations of penitence and mourning, especially as an ecclesiastical colour; in literary and poetic use, it may refer to the colour of blood.

Recorded from Old English (describing the clothing of an emperor) the word comes via Latin purpura ‘purple’ from Greek porphura, denoting molluscs that yielded a crimson dye, or cloth dyed with this.
Purple Heart in the US, a decoration for those wounded or killed in action, established in 1782 and re-established in 1932. Purple heart was also a slang term for amphetamines (from their colour and shape) in the 1960s.
purple passage an elaborate or excessively ornate passage in a literary composition; an alternative name is purple patch. The term is a translation of Latin purpureus pannus, and comes from the Roman poet Horace's Ars Poetica, ‘Works of serious purpose and grand promises often have a purple patch or two stitched on, to shine far and wide.’

See also born in the purple, Tyrian purple at Tyre.