tunnel

As a letter s

is the letter s with a.

As a noun tunnel is

tunnel.

Mine is a synonym of tunnel.

As a verb mine

is .

As an adjective mine

is mined.

As a noun tunnel is

tunnel.

As nouns the difference between tunnel and plug

is that tunnel is tunnel while plug is (electricity) a pronged connecting device which fits into a mating socket.

As a verb plug is

to stop with a plug; to make tight by stopping a hole.

As a noun tunnel

is tunnel.

As a verb ear is

(label) refuse, deny; repel.

As nouns the difference between mountain and tunnel

is that mountain is a large mass of earth and rock, rising above the common level of the earth or adjacent land, usually given by geographers as above 1000 feet in height (or 3048 metres), though such masses may still be described as hills in comparison with larger mountains while tunnel is tunnel.

As a noun tunnel

is tunnel.

As an adjective undefined is

lacking a definition or value.

As nouns the difference between tunnel and cellar

is that tunnel is tunnel while cellar is an enclosed underground space, often under a building; used for storage or shelter or cellar can be salt cellar.

As a verb cellar is

to store in a cellar.

As nouns the difference between tunnel and flyover

is that tunnel is tunnel while flyover is (us) a low-level flight, especially of military aircraft, of a ceremonial nature; a flypast (british).