Green’s Dictionary of Slang

1. (US Und.) a manual labourer, usu. nomadic.

1902		Dly Jrnl (Salem, OR) 26 July 1/3: The ‘dyno’ is the professional floating worker, who slaves in the mines or on railroad construction [...] and makes his way south where wheat cutting has begun.
1913		Omaha Dly Bee (NE) 14 Sept. 13/1: Dynos [...] the men who build the tracks of the railroad.
1927		‘Jargon of the Und.’ in DN V 445: Dyno, Pick and shovel men on railway and highway construction.
1962		Ragen & Finston World’s Toughest Prison 798: dyno – A pick and shovel worker.

2. (drugs, also dyno-pure) heroin.

1949		Monteleone Criminal Sl. (rev. edn).
1969		R.R. Lingeman Drugs from A to Z (1970) 88: dyno Relatively undiluted, high-potency heroin, often stronger than the addict is tolerant to.
2001		ONDCP Street Terms 8: Dyno — Heroin; Dyno-pure — Heroin.

3. (US prison) liquor.

1962

Ragen & Finston World’s Toughest Prison 798: dyno – Liquor.

4. see dino n.²