Q: How did “slug” come to mean either a good or a bad thing? As in, “The slugger hit a home run and ran sluggishly around the bases.” Perhaps the same derivation morphed into different connotations?
A: English has several distinct—that is, etymologically unrelated—senses of “slug.” One is the source of “slugger” and the other of “sluggishly.”
When “slug” first appeared in early Middle English (as “sluggi” or “sloggi”), it was an adjective meaning indolent or sluggish.
The Oxford English Dictionary’s earliest citation, which we’ve expanded, is from Ancrene Riwle (also known as Ancrene Wisse), an anonymous guide for monastic women, written sometime before 1200:
“hwa mei beon for schame slummi sluggi & slaw, þe bihalt hu bisi ure lauerd wes on eorðe” (“Who can, for shame, be sleepy, sluggish, and slow, who sees how very busy our Lord was on earth?”). The text cited by the OED uses “sluggi” where some other Ancrene Riwle manuscripts use “sloggi.”
The term “slug” later appeared in the verb “forslug” (to neglect by sluggishness). This Oxford example was written around 1315:
“Wanne man leteth adrylle / That he god ȝelde schel, / And for-sluggyth by wylle / That scholde men to stel” (“When a man lazily and willfully neglects his duties toward God and man”). From The Poems of William of Shoreham, vicar of Chart Sutton in Kent. (The University of Michigan’s Middle English Dictionary uses the thorn þ for the th digraph in its citation for the passage.)
The word “slug” appeared as both a noun and a verb around the same time in the early 15th century, according to the OED. The verb meant “to be lazy, slow, or inert; to lie idly or lazily,” the dictionary says, while the noun meant “a slow, lazy fellow; a sluggard” as well as the personification of slothfulness.
Oxford’s earliest citation for the verb, from the Life of St. Mary of Oignies, circa 1425, says Mary, a member of the Beguines, a lay religious order, “slugged neuer wiþ slouþe; she defayled in trauayle neuere or seldom” (“was never lazy with sloth; she grew weak from toil never or seldom”).
The dictionary’s first example for the noun is from The Castle of Perseverance, an anonymous morality play written around 1425:
“A, good men! be-war now all of Slugge & Slawthe, þe fowle þefe!” (“Ah, good men! Beware now all of Sluggishness and Sloth, the foul thief!”)
This slow, lazy sense of “slug” is the source of “sluggard” (1398), “sluggish” (c. 1450), “sluggishly” (c. 1450), and the slimy, slow-moving garden “slug” (1725). The dates are for the OED’s earliest citations.
An entirely different sense of “slug” appeared in the early 17th century, when the word came to mean “a piece of lead or other metal for firing from a gun,” the OED says. We haven’t seen any convincing theories for the source of this sense.
The dictionary’s first citation is a 1622 entry in mixed Latin and English from the court records of Durham, England: “Unum tormentum anglice a gun oneratum cum quadam plumbea machina vocata a Slugg” (“One English cannon loaded with lead ammunition called a Slugg”). From Quarter Sessions Rolls, Durham.
This sense of “slug” led to its use as a term for a strong drink (1756), a metal bar to mark a division in printing (1871), a counterfeit coin (1887), and an identifying title of a draft news story (1925), according to evidence in the OED.
We’ve wondered if the ammo sense of “slug” may also have inspired its use as a verb meaning to hit hard and a noun meaning a hard hit, but the OED doesn’t make that connection. It notes only that a somewhat earlier noun and verb spelled “slog” had the same hitting senses, but was “of obscure origin.”
John Ayto’s Dictionary of Word Origins suggests that the hitting “slug” and “slog” share a distinct etymology and “probably go back ultimately to the prehistoric Germanic base *slakh-, *slag-, *slog-, ‘hit’ (source of English slaughter, slay, etc.).”
The OED defines the noun “slug” here as “a heavy or hard blow; a beating.” The first Oxford citation is from a poem in the Geordie dialect of northeast England about the life of a coal miner in Newcastle:
“We’ll spend wor hin’most plack, / Te gi’e them iv’ry yen a slug” (“We’ll spend our last penny to give every one of them a slug”). From The Pitman’s Pay, or, A Night’s Discharge to Care (1830), by Thomas Wilson.
The earliest OED example for the verb used similarly is from a northern English dialectal dictionary: “SLUG. To beat. ‘Been an’ slugg’d muh wi’ a stick as thick as his neive [fist]!’’ From The Dialect of Leeds and Its Neighbourhood (1862), by C. Clough Robinson.
Getting back to your question, this hitting sense of the verb “slug” is the source of “slugger” used for a hard-hitting prize fighter or baseball player. The boxing sense was the first to show up.
The OED has an 1877 citation from The Underworld of Chicago (1941), by Herbert Asbury, that refers to two African-American boxers as “sluggers.” However, we couldn’t find the cited passage in searching three editions of the book for an expanded version.
The earliest boxing example we’ve seen is from an account of a match in Cincinnati “between Thomas Day of Scranton and Dan Callahan, ‘The Galway Slugger,’ of Louisville. The referee decided in favor of the Slugger, the score standing 7 to 4 in his favor.” From the New York Clipper, a sporting and theatrical weekly, May 22, 1880.
The term was often attached to the most famous fighter of his day, John L. Sullivan, as in this headline from a West Virginia newspaper about a match with Paddy Ryan: “SULLIVAN, THE SLUGGER: The Fighter and His Trainer in New Orleans—Confident of Victory” (Wheeling Register, Dec. 21, 1881).
The use of “slugger” in baseball appeared a few months later: “There are plenty of ‘sluggers’ and three-bagger batsmen, who do big things against poor pitching, but very few scientific hitters, who know how to place a ball, make a telling sacrifice-hit, or to earn a base well” (New York Clipper, May 6, 1882).