boxcar adjective 1noun 2verb 1forms 5 adjective1 •Extremely large. noun2 •(US) An enclosed railway goods wagon, typically with a sliding door.The locomotive pulled one single car, a dilapidated boxcar missing numerous planks in its walls. — 2016 •[before a noun] A type of atrophic acne scar that forms a broad, box-like depression on the skin. verb1 •To reduce to a boxcar function. formsboxcarred · boxcarring · boxcars · more boxcar · most boxcar