high altitude-high opening (HAHO)

high altitude-low opening (HALO)

high-altitude low-opening parachute technique (HALO)

high altitude

high- and low-altitude surveillance

high-altitude long-endurance (HALE)

high-altitude nuclear burst

surveillance, high- and low-altitude surveillance

theater high altitude air defense (THAAD) system

high altitude arrival waypoint

very-high-altitude missile

high-altitude rocket barrage

high-altitude helipad

high altitude pseudo satellite (HAPS)

high-altitude drone

high-altitude long endurance unmanned aerial vehicle

high-altitude unmanned aerial vehicle

high-altitude takeoff

create an opening

firing signals (opening, shifting, ceasing fire)

air intake opening

air inlet opening

belt opening

breech-opening mechanism

breech-opening motor

clear opening

cylinder block inlet opening

feed opening

magazine feed-piece opening

front-sight opening

limit of opening fire

frame around opening

valve opening lead