mask-n; 7 Senses

Sense Number 1: a physical disguise that covers the face

Commentary: MASK[+artifact][+covering][+face][+disguise]

The Lone Ranger wore a black mask to conceal his identity.
Mary tried on several Halloween masks.
The robber may have been a man wearing a clown mask.
The terrorists wore ski masks when they assaulted the building. (disguise usage)
They arranged their rendezvous under the mask of darkness. (metaphoric extension)
The dark fur around a raccoon's eyes is called a mask. (extended usage)

WordNet 3.0 Sense Numbers: 1

Sense Number 2: an intentional activity of concealment

Commentary: MASK[+activity][+concealment]

He dropped the mask of friendliness and spoke in a cold, authoritative voice.
She gradually became aware of the masks and facades he used for emotional protection.
The woman's cheerfulness at work was a mask to hide her underlying depression.

WordNet 3.0 Sense Numbers: 2

Sense Number 3: a costume party or ball

Commentary: MASK[+event][+party][+costume]
NOTE: refers to the whole party, not to the face coverings that are worn at it.

Mary received an invitation to the annual Mardi Gras mask.
At the mask, guests were dressed in 18th-century period costumes.

WordNet 3.0 Sense Numbers: 3

Sense Number 4: a protective covering for the face

Commentary: MASK[+artifact][+covering][+face][+protection][+gas/+surgical/+oxygen]
NOTE: function is to protect or aid, rather than disguise (see Sense 1)

The doctors donned their surgical masks before entering the operating room.
Fighter pilots wear oxygen masks while doing their aerobatic maneuvers.
Football players may not grab the face mask of another player.
The soldiers donned their gas masks for the military exercise.
A ski mask helps block out the wind and cold. (usage is to protect)

WordNet 3.0 Sense Numbers: 4

Sense Number 5: a cleansing paste for the skin, usually the face

Commentary: MASK[+substance][+paste][+cleansing][+skin]

Mary had a seaweed and mud mask at the spa.
These masks are peeled off the face once they are dry.

WordNet 0.0 Sense Numbers: 3e

Sense Number 6: a patterned covering used to block exposure to a chemical or light

Commentary: MASK[+artifact][+blocker][+patterned][+exposure][+prevention]

These masks are used to etch the circuits into silicon by exposing parts of the surface to chemicals and light.
The artist showed us the masks he used to create his silk screens.

WordNet 0.0 Sense Numbers: 4

Sense Number 7: a human or animal head, or a likeness thereof

Commentary: MASK[+structure][+anatomical][+head][+human/+animal]
NOTE: primary function is display, not disguise (see Sense 1)

John has an impressive collection of carved African masks.
The mask of an elk was mounted on the wall above the fireplace.
The death mask of the mummy was cast in gold.

WordNet 0.0 Sense Numbers: 2