A simpleton. The word appears as Gonnie, a. 1580: N.E.D.

1

1837–40.  That are Sheriff was a goney.—Haliburton, ‘The Clockmaker,’ p. 139. (N.E.D.)

2

1843.  How the goney swallowed it all.—‘Sam Slick in England,’ chap. xxi.

3

a. 1855.  A stupid fellow, a dolt, a boot-jack, an ignoramus, is called here a gonus.Dartmouth Mag., iv. 116 (Hall’s ‘College Words,’ p. 229).

4