断面 (danmen) means “cross section” | MotiTan Japanese Dictionary

More examples

りんごを切って、断面の形を確かめます。ri n go o ki tte dan men no katachi o tashi ka me ma su

I cut an apple and check the shape of its cross section.

Describes the surface revealed when an object is cut across, often showing its internal structure.

切り口kirikuchi: The surface exposed when an object is cut.
切断面setsudanmen: The surface formed where an object is separated by cutting.

物体をある面で切ったときに現れる切り口の形や面。but tai o a ru men de ki tta to ki ni arawa re ru ki ri kuchi no katachi ya men

The compound 断面 (danmen, "cross section") combines 断 (dan, "cut off") and 面 (men, "surface").

In science and medicine, a cross section makes hidden internal parts visible in diagrams and models.