English · Phrasal verb Attested

hair up

In real, traceable use. Part of the curated seed collection; community review is coming.

Sense 1

Both English Tiếng Việt

Meaning · English

To grow (more) hair. — To grow its longer, thicker winter coat.

Nghĩa · Tiếng Việt

Tăng trưởng (nhiều) lông

Machine-translated — suggest a fix

Where it’s used: Used American English

Examples

Earmarks supplement brands for owner identification. When a cow critter gets all haired up in a thick winter coat, a brand gets harder to read than an earmark.

Usage example from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30)

Sources & notes

Adapted from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30 via kaikki.org).

Sense 2

Both English Tiếng Việt

Meaning · English

To grow (more) hair. — To grow facial hair, especially after shaving; (rarely) to grow body hair.

Nghĩa · Tiếng Việt

Tăng trưởng lông mặt, đặc biệt sau khi cạo râu

Machine-translated — suggest a fix

Sources & notes

Adapted from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30 via kaikki.org).

Sense 3

Both English Tiếng Việt

Meaning · English

To cause the fur of (an animal) to puff up or stand on end.

Nghĩa · Tiếng Việt

Làm cho lông của động vật đứng lên

Machine-translated — suggest a fix

Sources & notes

Adapted from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30 via kaikki.org).

Topics: Hair

Common questions

What does “hair up” mean?

To grow (more) hair. — To grow its longer, thicker winter coat.

Is “hair up” formal or informal?

No register label has been reviewed yet — treat it as neutral and check the usage notes above.