Meaning

noun the brush (small trees and bushes and ferns etc.) growing beneath taller trees in a wood or forest

originThe name is from England or Scotland, and from Middle English. The surname is sometimes habitational, used by someone who lived in any of several places of the same name. Otherwise it is topographic, referring to someone who lived near a wood. The common noun comes from the name of the manufacturer, after John T. Underwood, one of its founders.

Etymology from Wiktionary, CC BY-SA 3.0