three-dimensional
three-frequency
three-gap
three-gun
three-halves
three-input
three-junction
three-level
three-neck
three-phase
  three-pole
three-port
three-position
three-program
three-step
three-terminal
three-vidicon
three-way
three-wire
threshold
thresholder

    three-pole switch

    трёхполюсный переключатель