Dictionary

mask up en · VERB

Popularized in 2020 during the COVID-19 pandemic. Before that, attested but not common outside technical contexts.

(intransitive) To put on a mask, especially a safety mask or a medical face mask.
- Winston arrived twenty-four hours ago. Before I can enter the ward where he lies, I need to mask up. In theory, the masks we all wear – paper thin, though reinforced with a water-resistant coating – will prevent the virus from contaminating our mouth or nose, even when a patient coughs in our direction. 2021, Rachel Clarke, Breathtaking: Inside the NHS in a Time of Pandemic, London: Little, Brown, →ISBN, page unknown:
- Soldiers are trained to immediately mask up at the first sign or suspicion that a chemical attack is in progress and then immediately give the signals themselves. In conjunction with any early warning of chemical attack, the donning of the protective mask will provide the best possible protection that the foot soldier has against airborne chemical agent attack. 2001, Eric R. Taylor, Lethal Mists: An Introduction to the Natural and Military Sciences of Chemical, Biological Warfare and Terrorism, Huntington, NY: Nova Science Publishers, →ISBN, page 181:

Spelling	Features	Source
masking up	Tense=Pres, VerbForm=Part	lexicographic
masks up	Number=Sing, Person=3, Tense=Pres	lexicographic
masked up	Tense=Past, VerbForm=Part	lexicographic
masked up	Tense=Past	lexicographic