n.(usually plural) when two dice are thrown and both come up showing six spots the result is called `boxcars'

It's Just A Road
BOXCARS: Crossed‐beam phase‐matched CARS generation in gases
Folded BOXCARS for rotational Raman studies
CARS microscopy with folded BoxCARS phasematching
Stored-Product Insect Populations in Boxcars Delivering Flour and Rice to Gulf Coast Ports
Three-dimensional view of signal propagation in femtosecond four-wave mixing with application to the boxcars geometry
Phase matching in femtosecond BOXCARS
BoxCars: 3D Boxes as CNN Input for Improved Fine-Grained Vehicle Recognition
Comments on the use of BOXCARS for gas‐phase CARS spectroscopy
Load securement system for boxcars or containers