Skulduggery is behaviour in which someone acts in a dishonest way in order to achieve their aim. accusations of political skulduggery. secretly dishonest or illegal activity - also used humorously (sculduddery (18-19 centuries))
(noun.) 1867. 1856, apparently an alteration of Scottish English sculdudrie (“adultery”), sculduddery “bawdry, obscenity”, a euphemism of uncertain origin.