noun

• (countable) A restraint or support, especially one consisting of a loop or network of rope or straps, and especially one worn by a working animal such as a horse pulling a carriage or farm implement.
• (countable) A collection of wires or cables bundled and routed according to their function: a wiring harness.
  "The cars then enter the main lines for further assembly - including the installation of internal electrical harnesses, underfloor equipment, internal panelling, roof equipment, carpets, seats and tables."
• (dated, uncountable) The complete dress, especially in a military sense, of a man or a horse; armour in general.
  "Ring the alarum-bell! Blow, wind! come, wrack! At least we'll die with harness on our back."

verb

• (transitive) To place a harness on something; to tie up or restrain.
  "They harnessed the horse to the post."
• (transitive) To capture, control or put to use.
  "Imagine what might happen if it were possible to harness solar energy fully."
• (transitive) To equip with armour.