Etymology tree Proto-Germanic *breustą Proto-West Germanic *breust Old English brēost Middle English brest English breast From Middle English brest, from Old English brēost, from Proto-West Germanic *breust, from Proto-Germanic *breustą, from Proto-Indo-European *bʰrews- (“to swell”). Compare West Frisian boarst, Danish bryst, Swedish bröst; cf. also Dutch borst, German Brust.