Green’s Dictionary of Slang

an old inhabitant, an old creature.

1903		D.S. Crumb ‘Dialect of Southeastern Missouri’ in DN II:v 327: residenter, n. Citizen; resident.
1912		R.W. Brown ‘Word-List From Western Indiana’ in DN III:viii 584: old residenter, n. Anything that reveals age or the toughness, strength, or wisdom of age. ‘It’s no use to try to catch that fish; the old residenter isn’t ready to have us cook him just yet.’.
1928		L. Mackay My Oul’ Town 74: An’ old ‘residenter’ said: ‘Jinny will laugh again when the spring comes round’.
1966		P. Boyle At Night All Cats are Grey 97: This was this real old residenter, long enough on the premises to claim squatter’s rights.