Green’s Dictionary of Slang

1. (US) an old-timer, an old person; a veteran, esp. a veteran convict; also attrib. [fig. use of SE].

1842		Wkly Rake (NY) 5 Nov. n.p.: the rake wants to knowIf the old head [...] thought it was not known that he used to peddle candies.
1864		J.F. Brobst letter in Brobst Well Mary, Civil War Letters 80: If they would let the soldiers settle this thing it would not be long before we would be on terms of peace, but a few old heads have got it in their hands and [...] will not settle it.
1893		‘Oliver Optic’ Fighting Joe (1911) 58: You are an old head at this business, and I am as green at it as a two months’ baby.
1927		‘Jargon of the Und.’ in DN V 457: Old head, A veteran convict.
1931		Irwin Amer. Tramp and Und. Sl. 136: Old Head.– Anyone with experience at any particular line of work or crime, or with a thorough knowledge of life.
1941		A. Lomax Mister Jelly Roll (1952) 86: He cause these younger Creoles, men like Bechet and Keppard, to have a different style altogether from the old heads.
1945		F.H. Hubbard Railroad Avenue 326: I thought you were an old head.
1955		L.F. Engler ‘Gloss. Air Force Sl.’ in AS XXX:2 119: OLD HEAD, n. A man who has been in the outfit a relatively long time.
1960		C. Cooper Jr Scene (1996) 76: Did those oldhead mackmen [...] think they were the only ones who could drive Hogs.
1965		J. Thompson Texas by the Tail (1994) 161: He talked the lingo like an old head.
1971–2		C. Shafer ‘Catheads [...] and Cho-Cho Sticks’ in Abernethy Bounty of Texas (1990) 210: old head, n. – an old convict; a convict that has been in prison for a long time.
1994		N. McCall Makes Me Wanna Holler (1995) 42: The old-heads said there was no place for love in a real man’s life.
2002		J. Lerner You Got Nothing Coming 172: The Old Heads are lifers and other convicts who have been down for decades.
2005		G. Pelecanos Drama City 107: Melvin was an old head who was into that old-type thing.
2008		R. Price Lush Life 24: Now it’s just the Old Heads out there sippin’ forties and telling stories about yesteryear .

2. (drugs) a long-time marijuana smoker; also attrib. [fig. use of SE, boosted by head n. (3a)].

1970

G. Scott-Heron Vulture (1996) 76: We all [...] made sure that we didn’t get bunted by a lot of goofs and old head dealers.