1. double flat a musical notation of two flats in front of a note indicating that it is to be lowered by two semitones
  2. double fault (tennis) two successive faults in serving resulting in the loss of the point
  3. double salt a solution of two simple salts that forms a single substance on crystallization
  4. double-faced (of fabrics) having faces on both sides
  5. double gold very tall branching herb with showy much-doubled yellow flower heads
  6. double play the act of getting two players out on one play
  7. double first a first-class honours degree in two subjects
  8. double talk deliberately unintelligible gibberish
  9. double-glaze provide with two sheets of glass
  10. double blind a test procedure in which the identity of those receiving the intervention is concealed from both the administrators and the subjects until after the test is completed; designed to reduce or eliminate bias in the results
  11. double date a date in which two couples participate
  12. double knit a knit fabric similar to jersey that is made with two sets of needles producing a double thickness joined by interlocking stitches
  13. doublet a man's close-fitting jacket, worn during the Renaissance
  14. double-date go out on a date with a partner and another couple
  15. fipple flute a tubular wind instrument with 8 finger holes and a fipple mouthpiece
  16. battle fleet a fleet of warships prepared for battle
  17. double feature two games instead of one
  18. double agent a spy who works for two mutually antagonistic countries
  19. double digit a two-digit integer; from 10 to 99
  20. double bond a covalent bond in which two pairs of electrons are shared between two atoms