丸材 is read as まるざい (maruzai) and means log.
まるざい
maruzai
まるたざい
round timber
まるい
curved
まるみ
mellowness
まる
circle
まるた
dace (Tribolodon hakonensis)
まるまる
entirely
まるめる
to lump together
まるぼん
reciter's book
まるで
as if
to become rounded
まるっきり
completely
まるめこむ
to roll up and put into (something)