How or why did "sock" come to mean "punch"?
I see that sock as an article of clothing is derived from Latin soccus for slipper. But, how did it also become a synonym for "a punch" or "to punch"?
It might be of Wolof origin. Here is an excerpt from The African Substratum in American English (by Margaret Wade-Lewis - 1988):
sock. The colloquial verb to sock means 'to hit or strike forcefully,' 'to punch,' 'to deliver a blow' (American Heritage. 1976: 1226). Its probable origin is the Wolof verb /s 1 k/ , meaning 'to beat with a pestle,' 'to strike' especially with something.
Note: Wolof (/ˈwɒlɒf/) is a language of Senegal, the Gambia, and Mauritania, and the native language of the Wolof people.
Moreover, the similar sounding verbs in English and Wolof are observed by the British linguist David Dalby in 1969 (from The Slavery Reader, Volume 1 By Gad J. Heuman, James Walvin):
The verb "sock," in the sense of "to strike," especially with something, has recently been popularized in the black American phrase "sock it to me" (with an obscene connotation), and is reminiscent of a similar-sounding verb in Wolof meaning "to beat with a pestle.
The Dictionary of Word Origins (by Joseph Twadell Shipley - 1945) has a different approach:
Sock, in the slang sense, to beat, is one of a series. When you urge a dog to sick 'im, the verb imitates the sound you make; a form of Seek him! (common Teut., AS. secan). One step stronger is to sock 'im ; the next stage, to soak 'im one!
Then, the same book includes the etymology of sick, soak, steep, sugar and stoop; and tries to make a connection:
If you are sick, the word is common Teut., AS. seoc. (Sickle is a diminutive, from L. secnla, from sccarc, to cut.) To soak, to steep, is fcom OE. socian, to suck in, a weak form of OE. sucan, whence Eng. suckj L. sh- gcrc, suet — , to suck; whence Eng. suction. A little one that sucks is a suckling; from this by backformation comes the verb, suckle. Sugar may have been influenced by L. sugere; it is win OFr. Sucre, from zuchrc, from LL. cuccarum, from Arab, sukkar. The verb to steep is from OE. steap, from OTeut. staupom, a vessel for water. The adjective steep is also from OE. steap, from OTeut. staup, stup; from this comes the OE. weak verb stupian, to lower, to bow, whence Eng. stoop. One will stoop to put on (or dodge) a sock.
Note: There might be typos in the excerpt. I copied and pasted the original text.
OED, World wide words, The Routledge Dictionary of Historical Slang, Oxford Dictionary of Modern Slang and some other similar sources; all say unknown origin. However, OED has the earliest citation from 1699:
Sock, to Beat... I'll Sock ye, I'll Drub ye tightly.
B. E. · A new dictionary of the terms ancient and modern of the canting crew · 1st edition, 1699 (1 vol.)
The origin is unclear according to Etymonline:
Sock:
- sock (v.1) 1700, "to beat, hit hard, pitch into," of uncertain origin. To sock it to (someone) first recorded 1877.
- sock (n.2) "a blow, a hit with the fist," 1700, from or related to sock (v.1)
Sock:
A blow; a beating. Chiefly in phr. to give (one) sock(s, to give a sound thrashing or beating. Also in phr. a sock in the eye (also fig.)
a 1700 B. E. Dict. Cant. Crew s.v. Tip, Tip the Culls a Sock, for they are sawcy, Knock down the Men for resisting.
1864 Slang Dict. 240 ‘Give him Sock,’ i.e. thrash him well. -
In the reference works that I consulted, the briefest answer offered to this question was also the most disappointing. From John Ayto, Arcade Dictionary of Word Origins (1990):
The origins of sock 'hit' {17[th century]} are not known.
Ernest Weekley, An Etymological Dictionary of Modern English, volume 2 (1921) has this:
sock2. To beat, to give socks. Cant, of unknown origin.
sock: a pocket, also to beat. I'll sock ye: I'll drub ye tightly (Dict. Cant. Crew).
The reference in Weekley is to A New Canting Dictionary (1725):
SOCK, a Pocket. Not a Rag in my Sock ; I han't a Farthing in my Pocket. Also to beat ; I'll sock ye ; I'll drub ye tightly.
So we have a firm occurrence of sock in the relevant sense from 1725, in a glossary entry that also identifies a slang meaning of sock as a noun ("a Pocket"). The juxtaposition here does not imply an etymological connection between the verb sock and the noun sock, however.
It may be tempting to connect the violent verb sock with the longer phrase "knock the socks off [someone]." But according to Glynnis Chantrell, The Oxford Dictionary of Word Histories (2002), that phrase is later and from the United States:
The phrase knock the socks off was originally US English from the early 19th century; ...
The only reference work I've found that actually hazards a guess as to the origin of sock as "hit or punch" is Eric Partridge, Origins: A Short Etymological Dictionary of Modern English (1966):
sock (3), to throw or hit violently: sl[ang]: o[f] o[bscure] o[rigin]: prob[ably] echoic.
A nice discussion of usage of sock in England circa 1900 appears in Notes and Queries (January 20, 1900), but nothing offered there as a possible source of the meaning is persuasive.
"Origin unknown" is the most accurate etymological conclusion to draw from these sources, I think.