deadly

1. 1
   adjective

   Causing death, or capable of causing it.

   The cobra delivers a deadly dose of venom in a single bite.

   Left untreated, the infection turned out to be deadly within a week.

   Similarlethal, fatal, mortal

   Oppositeharmless, benign

   Note

   The everyday sense compares in two ways, and both are standard. You can write deadlier and deadliest, or more deadly and most deadly. The short forms are common in serious prose: George Orwell's Nineteen Eighty-Four imagines scientists searching for "new and deadlier gases", and Naomi Sakr calls Iraq "one of the deadliest conflicts to cover". Choose by rhythm. The meaning does not change.

2. 2
   adverb

   To an extreme degree; used to intensify the word it modifies.

   The negotiators remained deadly earnest throughout the standoff.

   Her timing was deadly precise, never a beat off.

   Similarextremely, utterly, absolutely, completely

   Note

   The intensifier is far older than it sounds. Roger Boyle, Earl of Orrery, writes "deadly weary" in 1669, and John Arbuthnot's History of John Bull describes "so deadly cunning a man". It stands directly before the adjective it strengthens and adds weight without any thought of death. It is still at home with words like earnest and precise.

3. 3
   adjective

   Filled with hostility fierce enough to seek another's destruction; implacable.

   The rival warlords remained deadly foes until both were dead.

   A deadly feud divided the village for decades.

   Similarmortal, bitter, implacable, sworn

   Note

   The hostility lies in the intent, not the outcome. A deadly enemy wants you destroyed, whether or not they ever manage it. The classic pairing is deadly enemies, and the same idea runs through deadly foes and a deadly feud. In Shakespeare's Twelfth Night a man is warned that his assailant is "quick, skilfull and deadly", where the word means a skilled and determined fighter more than a sure killer.

4. 4
   adjective

   Highly accurate in aim, as with a bow or firearm.

   The sniper proved deadly at long range, missing almost nothing.

   Famous for a deadly throwing arm, he rarely missed the mark.

   Similaraccurate, unerring, precise, lethal

   Oppositeinaccurate, erratic

   Note

   Here deadliness is a matter of skill rather than danger. The word praises a shooter's accuracy, and its natural home is the phrase deadly aim. That phrase moved easily into argument and reform. George Swann's The Autumn Wreath (1869) speaks of reform carried "with deadly aim to crush foul bribery." Keep it apart from the "lethal" meaning: a marksman can be deadly at a target range without harming anyone.

5. 5
   adverb

   In a manner suggestive of death, such as extreme stillness or paleness.

   He lay deadly still on the cot, and we feared the worst.

   The corridor fell deadly silent the moment the alarm stopped.

   Similardeathly

   Note

   An adverb that sits in front of adjectives of pallor and stillness, as in deadly white, deadly still and deadly silent. Each phrase calls up the color or quiet of a corpse, so the intensity works by likeness. That picture is what separates it from the plain intensifier "extremely", where the thought of death has faded and only the degree remains.

6. 6
   adjectivecolloquial

   Extremely dull or tedious; thoroughly boring.

   The conference dragged on through one deadly session after another.

   His speeches were so deadly that half the audience dozed off.

   Similarboring, dull, tedious, tiresome

   Oppositeexciting, riveting, interesting

   Note

   Boredom borrows the vocabulary of death here, and the word sits comfortably before a noun or after a verb. Agatha Christie's The Mysterious Affair at Styles calls life with old aunts in Yorkshire "a deadly life". That is the same phrase that once meant the obsolete "mortal" sense, so context decides. Oliver Sacks lists textbooks as "flat, impersonal, deadly". The natural opposite is stimulating, as in a deadly lecture versus a stimulating one.

7. 7
   adjectivedialectalIrelandNewfoundland

   Excellent, impressive, or admirable; a strong expression of approval.

   Everyone reckoned the new mural down by the river was deadly.

   He gave a deadly speech at the gathering, and the whole mob cheered.

   Similarawesome, brilliant, excellent, great

   Oppositeawful, terrible, lousy

   Note

   Praise turns the word upside down in Australian Aboriginal English, and in informal Irish and Newfoundland speech as well. In these varieties a deadly mural or a deadly speech is a fine one. Outside those communities, listeners may hear the "boring" meaning or simply lethal. Use it where the approving sense is shared, or let the context make the praise unmistakable.

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