noun
split log; split timber
Refers to wood that has been split, often for fuel or construction. Common in forestry and traditional building contexts.
割り材をストーブにくべる。
Put split logs into the stove.
noun
A non-alcoholic beverage used to dilute or mix with spirits, such as soda, tonic water, or juice. Often used in bars and cocktail recipes.
ウイスキーの割り材に炭酸水を使う。
Use soda water as a mixer for whiskey.
Compound of 割り (splitting) + 材 (material, lumber). The drink mixer sense is a semantic extension, likening the mixer to something that 'splits' or dilutes the alcohol.