unicorn

As a verb mentioned

is (mention).

As a noun unicorn is

a mythical beast resembling a horse with a single, straight, spiraled horn projecting from its forehead.

As a noun unicorn

is a mythical beast resembling a horse with a single, straight, spiraled horn projecting from its forehead.

As an adjective undefined is

lacking a definition or value.

As nouns the difference between bicorn and unicorn

is that bicorn is (mathematics) a plane curve having two cusps while unicorn is a mythical beast resembling a horse with a single, straight, spiraled horn projecting from its forehead.

As an adjective bicorn

is having two horns.

As nouns the difference between unicorn and pelican

is that unicorn is a mythical beast resembling a horse with a single, straight, spiraled horn projecting from its forehead while pelican is pelican (any of various seabirds of the family pelecanidae).

As nouns the difference between hobgoblin and unicorn

is that hobgoblin is a small, ugly goblin that makes trouble for humans while unicorn is a mythical beast resembling a horse with a single, straight, spiraled horn projecting from its forehead.

As nouns the difference between teacup and unicorn

is that teacup is a small cup, with a handle, used for drinking tea; normally sits in a saucer as part of a tea set while unicorn is a mythical beast resembling a horse with a single, straight, spiraled horn projecting from its forehead.

As an adjective teacup

is of an animal, smaller than average.