"flame, fire," O.E. blæse "a torch, flame, firebrand, lamp," from P.Gmc. *blas- "shining, white" (cf. O.S. blas "white, whitish," M.H.G. blas "bald," originally "white, shining," O.H.G. blas-ros "horse with a white spot," M.Du., Du. bles, Ger. Blesse "white spot"), from PIE base *bhel- (1) "to shine, flash, burn" (see bleach). The verb is early 13c.
"light-colored mark or spot," 1630s, northern Eng. dialect, probably from O.N. blesi "white spot on a horse's face" (from the same root as blaze (1)). A Low Ger. cognate of the O.N. word also has been suggested as the source. Applied 1660s in Amer.Eng. to marks cut on tree trunks to indicate a track; thus the verb meaning "to mark a trail;" first recorded 1750, Amer.Eng.
"make public" (often in a bad sense, boastfully), late 14c., from M.Du. blasen "to blow" (on a trumpet), from P.Gmc. *blaes-an, from PIE *bhle-, var. of base *bhel- "to swell, blow up" (see bole).