two-by-four
noun [ C or U ] uk/ˌtuː.baɪˈfɔːr/ us/ˌtuː.baɪˈfɔːr/
2x4尺寸;2x4的木料（或建材）（用于建筑的成木标准尺寸，略短于2吋宽及4吋深，可切割成不同长度）
a standard size of finished wood used for building that measures slightly less than two inches wide and four inches deep and can be cut to various lengths, or wood of this size
You'll need four eight-foot two-by-fours to frame out that wall. 要构建那面墙的框架，你需要四块2x4吋、8呎长的木材。
a two-by-four board 一块2x4吋板