Green’s Dictionary of Slang

masher n.

[mash v. (2); senses 2 and 3 are often elided]

1. [late 19C] an individual, of either gender, who uses charm and beauty to succeed.

2. [late 19C+] (orig. US) a man who forces his unwanted attentions on women, a ‘lady-killer’; also attrib.

3. [late 19C–1910s] a dandy, occas. masheress, the female version; thus masher blue, a shade of blue favoured by such men for their waistcoats.

4. [1990s+] (US black) a hard, committed worker.

In derivatives

masherette (n.)

[late 19C] (Aus.) the female equivalent of sense 2.

masherdom (n.)

[late 19C] the world of mashers.

In compounds

mashers corners (n.) [one could best ogle the chorus-girls from the front stalls]

[late 19C–1900s] (UK society) the opposite prompt (O.P.) and prompt side (P.S.) entrances to the stalls at the Gaiety Theatre, London.