Definition of "horselaugh"

Let realism have its demonstration, comedy its criticism, or even bawdry its horselaugh at the expense of sexual infatuation, if it must; but to ask us to subject our souls to its ruinous glamour, to worship it, deify it, and imply that it alone makes our life worth living, is nothing but folly gone mad erotically—a thing compared to which Falstaff's unbeglamored drinking and drabbing is respectable and rightminded.

1901, [George] Bernard Shaw, “Three Plays for Puritans”, in Three Plays for Puritans: The Devil’s Disciple, Cæsar and Cleopatra, & Captain Brassbound’s Conversion, London: Grant Richards, […], page xxix