Green’s Dictionary of Slang

broad adj.

[var. on wide adj. (1)]

1. [mid-19C–1900s] knowing, alert, ‘on the ball’; if not actually criminal then willing and able to bend any rule.

2. [1990s+] (W.I.) physically large; socially important.

SE in slang uses

In compounds

broad-arsed (adj.) [arse n. (1)]

[late 19C+] having wide hips.

broadbrim (n.) [the broad-brimmed hats adopted by many members of the Society of Friends]

1. [early 18C–mid-19C] a Quaker; thus broad-brimmed, sedate.

2. [mid–late 19C] a quiet, sedate old man, irrespective of religion.

broadbrow (n.)

[1920s] a person of wide tastes and interests.

broad-gauge lady (n.) [a pun on her breadth, and a ref. to the broad-gauge railway tracks, 7ft (1m) wide, which were abandoned when British railways were standardized at 4ft 8½in (44m) in the 1890s]

[late 19C] a woman with wide hips.

In phrases

broad in the beam (adj.) [beam n.1 ]

[late 19C+] fat, overweight, esp. around the hips and buttocks.