noun

• (originally US, slang) A bruise-like mark made during petting by pressing the mouth to the skin on one’s partner’s body and sucking.
  "But Louis Vuitton bras all over your breasts / Got me wanting to put hickeys all over your chest"
• (informal, slang) An object whose name is unknown or cannot be recalled.
• (printing) A printing defect caused by foreign matter on the printing surface resulting in a ring where the ink is missing, appearing as a spot of ink surrounded by a halo, or as an unprinted spot within a solid printed area.
• (printing, informal) A serif or other ornamentation on type.
  "Years ago, there were internal company standards for dark center (ink color) hickeys and for white voids in solids/type."