- two units thick and four units wide, especially in inches.
- lacking adequate space; cramped: a small, two-by-four room.
- unimportant; insignificant: Theirs was a petty, two-by-four operation.
- a timber measuring 2 × 4 inches (5 × 10 centimeters) in cross section, when untrimmed: equivalent to 1 5/8 × 3 5/8 inches (4.5 × 9 centimeters) when trimmed.
- a length of untrimmed timber with a cross section that measures 2 inches by 4 inches
- a trimmed timber joist with a cross section that measures 1 1/2 inches by 3 1/2 inches
