Anything not readily explainable appearing to move through or be suspended in the air, primarily used to refer to objects that seem to be at least of small familiar aircraft size. Abbreviated UFO.

A universal address for resources on the internet, which is most commonly used for websites.

(not comparable) Being the only one of its kind; unequaled, unparalleled or unmatched. / Of a feature, such that only one holder has it. / Particular, characteristic.

A thing without a like; something unequalled or unparallelled; one of a kind.

(mathematics) the interval [0,1], that is the set of all real numbers x such that zero is less than or equal to x and x is less than or equal to one / (telecommunications) symbol duration time.

simple past tense and past participle of unite

Joined into a single entity. / Involving the joint activity of multiple agents.

(transitive) To bring together as one. / (reciprocal) To come together as one.

(UK, historical) A British gold coin worth 20 shillings, first produced during the reign of King James I, and bearing a legend indicating the king's intention of uniting the kingdoms of England and Scotland.

(biology) Describing any microorganism that has a single cell