adj

• Relating to heat and conditions which produce it.
  "He forgot that the frying pan was hot and burned his hand."
• Relating to heat and conditions which produce it.
  "I was so hot from being in the sun too long."
• Active, in use or ready for use (like a bullet or a firing range), turned on (like a microphone or camera).
  "a hot wire"
• Active, in use or ready for use (like a bullet or a firing range), turned on (like a microphone or camera).

noun

• (electronics) Acronym of hybrid-orientation technology (“CMOS fabrication technology that uses PMOS and NMOS substrates with differing orientations”).
• (electronics) Acronym of hybrid-orientation technique, a technique that applies the technology.
• (automotive) Acronym of high-output turbo (turbocharger).
• (traffic control) Acronym of high occupancy or toll lane.

adj

• (traffic control) Acronym of high occupancy or toll.