Emily Dickinson Lexicon

FAL'LOW, a. [Sax. falewe, falu or fealo; D. vaal; G. falb, fahl; Fr. fauve, for falve; L. fulvus; qu. helvus, for felvus. This word may be from the root of fail, fallo; so called from the fading color of autumnal leaves, or from failure, withering. Hence also the sense of unoccupied, applied to land, which in Spanish is baldio.]

1. Pale red, or pale yellow; as, a fallow deer.
2. Unsowed; not tilled; left to rest after a year or more of tillage; as, fallow ground; a fallow field. Break up your fallow ground. Jer. iv.
3. Left unsowed after plowing. The word is applied to the land after plowing.
4. Unplowed; uncultivated. Tooke. Shak.
5. Unoccupied; neglected. [Not in use.] Let the cause lie fallow. Hudibras.