Green’s Dictionary of Slang

bushwa n.

1. [20C+] (also booshwah, boushwah, bushwah, bushwash) nonsense, euph. for bullshit n. (1) [f. bullshit n. (1), but ? link to Can. bois de vache, buffalo dung].

2. attrib. use of sense 1.

3. [1920s] (also boushwa) a pretentious, arrogant person [f. Can. bourgeois, the head voyageur of a trading post or expedition].

4. [1940s] a yokel.

5. [1940s] (US Und.) an outsider who dislikes criminals.