Lumber
Timber, Wood
noun
Lumber trees are what you use to make lumber and timber.
ざいもく
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
なんで材木にクイックルワイパーをかけてるの？
Why are you mopping that wood with a Quickle wiper?
あの材木おき場に夜の八時に行くと、神様に会えるらしいよ。
I heard that if you go to the lumber yard at 8 p.m. you'll be able to meet God.
材木が来たらすぐに犬小屋作りに取り掛からないとな。
We should get started building the doghouse as soon as the lumber gets here.