Green’s Dictionary of Slang

spade n.

[SE phr. black as the ace of spades; poss. derog. in the US, it is seen as a neutral/affectionate term in the UK; Kuethe, ‘Prison Parlance’, American Speech IX:1 (1934), defines as ‘a very dark Negro’]

1. [1910s+] (orig. US) a black person, esp. West Indian or African.

2. an Indian.

In derivatives

Spadesville (n.)

(US) the black area of a town or city.

In phrases

queen of spades (n.) [queen n. (2)]

(US gay) a respected black homosexual.

SE in slang uses

In compounds

spadework (n.)

[1980s] (S.Afr. campus) flirtation.

In phrases

call a spade a (bloody) shovel (v.) [a play on the SE phr. call a spade a spade]

[1910s+] to speak aggressively or vehemently.

in spades (adv.) (also in chunks) [SE spade, i.e. ‘spadefuls’; note in cards spades are the highest suit]

[1920s+] (orig. US) to the greatest extent, very much, extremely, any form of intensifier; thus you can say that in spades, you couldn’t be more right.