Definition of "Jemmy"

Joly Jemmy, [i.e. James IV of Scotland] ye scornefull Scot,Is it come unto your lotA solempne sumner for to be?

1513, John Skelton, Agaynst the Scottes; republished in John Scattergood, editor, John Skelton: The Complete English Poems, 1983, page 116, lines 49–51