thumb, n. — Green’s Dictionary of Slang

thumb n.

1. (US) an act of dismissal.

1960

J. Brosnan Long Season 80: Solly kicked dirt on the umpire’s pants, blew smoke up his nose, threw his cap on the ground, and was given the thumb in a most cursory dismissal.

2. (drugs) marijuana, a marijuana cigarette [one suck it].

1969		R.R. Lingeman Drugs from A to Z (1970) 241: thumb A fat marijuana cigarette.
1972		E. Shrake Strange Peaches 208: [T]he joints grew into Camels, chalk sticks, Thumbs, Torpedoes and even Corona Supremes.
2001		ONDCP Street Terms 21: Thumb — Marijuana.

SE in slang uses

In compounds

thumb-snag (v.)

(US) to hitchhike.

1958

W. Motley Let No Man Write My Epitaph (1959) 80: ‘Man, how’d you-all git here?’ ‘Ah grabbed a freight and Ah thumb-snagged.’.

In phrases

absolutely thumbs (adj.)

excellent.

1919

Chips (comic) 5 July 1: ‘Some joy trip! what!’ ‘It’s absolutely thumbs!’ chortled Willie.

get one’s thumb out of one’s ass (v.)

see get one’s finger out under finger n.

get the thumb (v.) [the umpire’s thumb points to the dugout]

(US) to be ejected from a sporting (esp. baseball) game.

1994

M. Ribowsky Don’t Look Back 54: Enraged that Satch could get the thumb even though Murray began the fight, Bill Gatewood pulled his team off the field.

give someone the rub of the thumb (v.) [the gesture of rubbing one’s thumb against the forefinger]

to impart information to someone.

1890–1904

Farmer & Henley Sl. and Its Analogues.

sit there/stand around with one’s thumb up one’s ass (v.)

see sit there with one’s finger up one’s ass under ass n.

thumb in bum and mind in neutral [bum n.¹ (1)]

(orig. Aus.) a phr. used of one who seems to have fallen into a vacant reverie.

1984

Partridge DSUE (8th edn) 1227: from ca. 1960.

thumb in one’s eye (n.)

(US) an irritation, an annoyance.

2003

Guardian 24 Nov. 🌐 Cash isn’t always king (just a black hole for British tennis) and professionalism is sometimes a thumb in the eye: but together they can still spell revolution.

thumb of love (n.)

the penis.

1890–1904

Farmer & Henley Sl. and Its Analogues.

weigh one’s thumb (v.) [the age-old practice of a shopkeeper keeping his thumb pressing on the scales when weighing goods]

to give short measure.

1896

Daily Tel. 25 Aug. in Ware (1909) 260/2: For practising the old trick of ‘weighing his thumb’ to the disadvantage of the customer, a City coster, named James Martin, who said he thought it ‘a light affair’, was directed to pay a fine of 20s. and costs.