letterbox (aspect ratio of film transferred to video)

checkbox (a window item, on the computer screen, which toggles check/uncheck by a single click)

beatbox

minivan

horizon on water / a horizontal or level line (perpendicular to the force of gravity)

horizon on land

Red Square (a square in Moscow, Russia)

a red paper lantern, typically used as a sign marking an izakaya, an inexpensive Japanese pub / (figuratively) an izakaya

a red papier-mâché bobblehead cow toy, a kind of regional omiyage regarded as symbolic of the Aizu region of Japan

red lead