kachin-kochin
Frozen completely solid with absolutely no give — a stronger, more emphatic variant of kachi-kachi. Used for things frozen so hard they could break a tooth, like ice cream straight from the freezer.
💡Used for roads frozen into ice sheets, meat frozen solid in a freezer, or water pipes frozen through.
水道管がかちんこちんに凍ってしまった。
The water pipes froze absolutely solid.
The puddle was ___ frozen solid this morning.
今朝、水たまりが___に凍っていた。