semi-drying oil

It's considered a semi-drying oil, unless modified.

A semi-drying oil is an oil which partially hardens when it is exposed to air.

Niger seed oil is polyunsaturated semi-drying oil.

Sesame oil is a polyunsaturated (PUFA) semi-drying oil.

This is as opposed to a to drying oil, which hardens (through polymerization) completely, or a semi-drying oil, which partially hardens.

The kernel of the egusi-itoo seed contains semi-drying oils which can be used for making soaps, cooking and for illumination, with the rest of the seed fed to livestock.