I. ˌtü-bī-ˈfȯr noun
Date: 1884
: a piece of lumber approximately 2 by 4 inches as sawed and usually 1 5/8 by 3 5/8 inches when dressed
II. adjective
Date: 1897
1. : small or petty of its kind
this house and its two-by-four garden — Philip Barry
2. : measuring two units (as inches) by four