# deadly

/ˈdɛdɫi/ (US) · /dˈɛdli/ (UK)

Source: https://englishreference.com/word/deadly
Updated: 2026-06-19

## Senses

### 1. lethal

adjective · CEFR B2

able to cause death.

For teachers: capable of causing death; lethal or fatal in effect.

- The cobra has a deadly bite that can kill a person in hours.
- The researchers discovered that even a minute dose of the toxin proved deadly to most mammals within the ecosystem.

### 2. extremely accurate

adjective · CEFR B2

very accurate and effective, especially when aiming a weapon or a ball.

For teachers: highly accurate or effective; unerring in aim or execution.

- The striker has a deadly shot that rarely misses the goal.
- His reputation as a deadly marksman ensured that few dared to challenge him in the regional competition.

### 3. very boring

adjective · CEFR C1 · Informal

extremely dull or uninteresting.

For teachers: extremely dull, tedious, or monotonous. Informal in register.

- The three-hour lecture on tax law was absolutely deadly.
- The meeting was so deadly that several board members were visibly struggling to remain awake during the financial presentation.

### 4. excellent

adjective · CEFR C2 · Informal · Dialect

very good or cool.

For teachers: excellent, impressive, or highly desirable. Primarily used in Irish and Newfoundland dialects.

- That new jacket you bought is deadly.
- The local band played a deadly set at the pub last night, drawing a massive crowd from the surrounding villages.

Teaching tip: This sense is specific to certain regions like Ireland; learners should be aware it may not be understood in the US or UK.

### 5. extremely

adverb · CEFR B2

used to emphasize an adjective, meaning 'very' or 'completely'.

For teachers: used as an intensifier meaning extremely or utterly; often collocates with 'serious', 'dull', or 'quiet'.

- The room went deadly quiet when the principal walked in.
- The CEO was deadly serious when she announced that the company would be restructuring its entire European division.

Usage: Commonly used in the fixed phrase 'deadly serious'.

## Examples

- The snake has a deadly bite.
- The soldiers faced a deadly combination of freezing temperatures and limited food supplies.
- While the protagonist's aim was deadly, his social skills were famously lacking, making the long dinner parties feel like a different kind of torture.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.