I wonder what the origin of "deadly" as "very good" and "excellent" is in Irish and Australian English. For example, a satisfied hotel guest might say, "The staff were very friendly and helpful. The room was really nice and the breakfast was deadly." Actually, many etymology dictionaries like Etymonline only refer to the origin of "deadly" as "mortal" or "fatal".

  • I wonder if it’s… deadly accurate/dead on target/deadly/dead on ?
    – k1eran
    Commented Apr 12, 2022 at 7:44
  • We also say in British English, "that was dead good!", meaning it was excellent. So it's not just Australian or Irish English. Commented Apr 12, 2022 at 10:23
  • 3
    @MoziburUllah, "Dead" in "dead good" is an adverb meaning "very". It's like "dead easy" or "dead hungry". So I don't think it's related to "deadly" as "excellent", which is an adjective.
    – BeatsMe
    Commented Apr 12, 2022 at 10:32
  • 2
    In American English you might hear that something is "to die for"
    – Drake P
    Commented Apr 12, 2022 at 17:02
  • 2
    Similar to "killer."
    – The Z
    Commented Apr 12, 2022 at 22:20

2 Answers 2


According to the following Macquarie Dictionary Blog the origin of deadly with a positive connotation is still unknown:

The word deadly with its current meaning was originally coined in the 1900s. It was then adopted into Aboriginal English in the 1970s and from then into general use.

Excellent, fantastic, cool: That movie was deadly! It is also used as an adverb, as in: he sang deadly.

Interestingly, deadly is also used in Ireland with the same positive meaning. Where you hear the lyrical tones of the many Irish migrants to Australia, a shout of deadly won't be far behind. There is also the term for a bicycle in Australia dating from the 1960s, deadly treadly, though the origin of this term is unknown.

but its usage most likely derives from the following tendency suggested by the site mentalfloss.com:

One of the main reasons for the existence of slang is to keep the outsiders from understanding the insiders. Making up new words is one way to achieve this, but it’s not the only one. A favorite trick for the young to play on the old is to take an established word and completely change its connotations from bad to good. In recent decades we’ve seen sick, wicked, ill, and bad recruited to the “hearty positive endorsement” side.

and, as noted by GDoS its original usage is from “black/campus” AmE:

deadly adj. [on bad = good model] (orig. US black/campus) excellent, first-rate:

  • 1907 [US] W.M. Raine Wyoming (1908) 234: Chalkeye was deadly on the shoot, and was ready for it at the drop of a hat.

  • 1941 [US] Life 27 Jan. 78: An orchestra that [...] sends [...] is called deadly [W&F].

  • 3
    "deadly on the shoot" has some logic: a deadly shot (one that kills) is a good shot. Perhaps that's the original? Commented Apr 12, 2022 at 15:58

"Deadly" might be an updated version of the phrase "to die for". Your example statement could be written: "The room was really nice and the breakfast was to die for."

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