Green’s Dictionary of Slang

bashing n.

1. (UK Und.) a judicial flogging.

2. [late 19C+] a beating; also in fig. use; thus gay-bashing under gay n.1 ; Paki-bashing under Paki n.; queer-bashing under queer n. [bash v. (1)].

3. [1920s+] masturbation [bash v. (4)].

4. [1930s+] prostitution [bash v. (6)].

5. [1970s+] verbal aggression, from severe criticism to affectionate teasing; ; esp. in sfx form -bashing, e.g. union-bashing, anti-Union behaviour/comments [bash v. (8)].

In phrases

take a bashing (v.)

[1940s+] (orig. milit.) to suffer heavy losses, to do badly.