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.
[late 19C] (Aus.) the female equivalent of sense 2.
[late 19C] the world of mashers.
[late 19C–1900s] (UK society) the opposite prompt (O.P.) and prompt side (P.S.) entrances to the stalls at the Gaiety Theatre, London.