broad (adj.) Look up broad at Dictionary.com
Old English brad "broad, flat, open, extended," from Proto-Germanic *braithaz (cognates: Old Frisian bred, Old Norse breiðr, Dutch breed, German breit, Gothic brouþs), of unknown origin. Not found outside Germanic languages. No clear distinction in sense from wide. Related: Broadly. Broad-brim as a style of hat (1680s, broad-brimmed) in 18c.-19c. suggested "Quaker male" from their characteristic attire.
broad (n.) Look up broad at Dictionary.com
"woman," slang, 1911, perhaps suggestive of broad (adj.) hips, but it also might trace to American English abroadwife, word for a woman (often a slave) away from her husband. Earliest use of the slang word suggests immorality or coarse, low-class women. Because of this negative association, and the rise of women's athletics, the track and field broad jump was changed to the long jump c.1967.