| 1. herbaceous plant with sour-tasting edible leaves; reddish-brown color; reddish brown horse. reddish-brown. sorrelsorrel , a. [f. saur, saure, of. sor, sore, probably of teutonic origin; cf. d. zoor dry, lg. soor; the meaning probably coming from the color of dry leaves. see: sear, a., and cf. sorel.] of a yellowish or redish brown color; as, a sorrel horse.sorrel sorrel , n. a yellowish or redish brown color.sorrel sorrel, n. [f. surelle, fr. sur sour, fr. ohg. s r sour. see: sour.] (bot.) one of various plants having a sour juice; especially, a plant of the genus rumex, as rumex acetosa, rumex acetosella, etc |