noun
split firewood
Refers to firewood that has been split into smaller pieces, ready for use in a stove or fireplace.
冬に備えて割り木をたくさん用意した。
We prepared a lot of split firewood for the winter.
薪 is a more general term for firewood, which may include unsplit logs or kindling, while 割り木 specifically refers to split pieces.
Compound of 割り (wari, 'splitting', from 割る) and 木 (ki, 'wood').