Vulnerable vs Weak

When to use each in English, with meaning, register, and examples.

Vulnerable

Top 2,000 (common) C1 adjective

Weak

Top 1,000 (very common) A2

Most common: Weak

	Vulnerable	Weak
Pronunciation	🇬🇧 //ˈvʌlnərəbl// 🇺🇸 //ˈvʌlnərəbəl//	🇬🇧 /["/wiːk/"]/ 🇺🇸 /["/wiːk/"]/
Meaning	Able to be easily harmed or hurt.	Not strong or powerful.
Example	Children are especially vulnerable to bullying at school.	She felt weak after running the marathon.
Register	Neutral	Neutral
How common	Top 2,000 (common)	Top 1,000 (very common)
CEFR level	C1	A2
Part of speech	adjective
Collocations	vulnerable population, vulnerable position, vulnerable state	appear, be, feel, extremely, fairly, very, at, from, in, weak at the knees, appear, be, feel, extremely, fairly, very, at, from, in, weak at the knees, appear, be, feel, extremely, fairly, very, at, from, in, weak at the knees
Antonyms	invulnerable, protected, safe	strong, powerful, robust
Common mistakes	Confused with 'invulnerable', which means incapable of being wounded., Used inappropriately in informal contexts when describing strong entities., Omitted the context of emotional vs physical vulnerability.	Confused with 'week' (the time period), Using 'weak' to describe intelligence instead of 'not intelligent', Overusing 'weak' to describe emotions, which can be seen as negative or stigmatizing
Usage notes	Used to describe people, animals, or things that are weak or exposed to harm. Appropriate in both formal and informal settings.	Used to describe physical strength, emotional resilience, or ineffective arguments. Avoid using it in formal academic contexts to describe theories or ideas.

See it in real clips

...and that makes your thoughts vulnerable to theft.

Vulnerable

shepherds the weak through the valley of darkness,

House Of Dragons › S1 E1

You're weak, viserys.

Succession › S1 E1

I hear it played weak. Conflict-averse.

shepherds the weak through the valley of darkness,

House Of Dragons › S1 E1

You're weak, viserys.

Weak

Frequently asked questions: Vulnerable vs Weak

What's the difference between Vulnerable and Weak?

Vulnerable: Able to be easily harmed or hurt. Weak: Not strong or powerful.

Which is more common: Vulnerable and Weak?

Weak is the most common in everyday English.

Which is more advanced: Vulnerable and Weak?

Vulnerable is the highest level, at C1, on the CEFR scale.

Are Vulnerable and Weak the same CEFR level?

Vulnerable: C1, Weak: A2 on the CEFR scale.

Can you show an example of each?

Vulnerable: Children are especially vulnerable to bullying at school. Weak: She felt weak after running the marathon.

Can I use Vulnerable and Weak interchangeably?

Not always. Vulnerable and Weak are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.