Question 1

What does "mask up" mean?

Accepted Answer

To put on a face mask as a public health measure or for safety protection.

Question 2

How do you use "mask up" in a sentence?

Accepted Answer

The sign at the hospital entrance told everyone to mask up before going inside.

Question 3

Is "mask up" formal or informal?

Accepted Answer

"mask up" is informal — used mainly in casual conversation. Became widely used during the COVID-19 pandemic (2020 onwards) as a public health instruction. Also used in industrial or hazardous work environments. Can be used as a direct command: 'Mask up!' The frequency of this phrase increased dramatically after 2020.

mask up

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