The basic meaning of the prefix uni- is “one.” It comes from the Latin prefix uni-, from the word unus, meaning “one.” Many English words beginning with uni- were formed in Latin. The word unicorn, for example, comes from uni- plus cornu, meaning “horn” and refers to a one-horned animal. Uniform comes from uni- plus forma, “shape,” and means “always the same” or literally “one shape.” And unison, which comes from uni- plus sonus, “sound,” means literally “one sound.” The majority of new words with uni-, such as unicellular, unicycle, unilateral, and univalent, are from the 19th century. Uni- can be compared to the prefix mono-, which is from Greek.
