A unibrow or monobrow, medically known as a synophrys, refers to a "confluence of eyebrows"; i.e. the presence of abundant hair between the eyebrows, so that they seem to converge to form one long eyebrow.
The words unibrow and monobrow are in the Oxford English Dictionary, and unibrow was added to the Merriam-Webster Dictionary in 2006. Medical dictionaries, such as Dorland's Medical Dictionary, contain the word synophrys.
In Western perception, a unibrow may make a person seem unattractive, so much so that the unibrow has become something of a cliché in fiction, especially with cartoon characters.
Among Western women, the region between the brows is often plucked, waxed, shaved, or treated with electrolysis or other forms of depilation. Unibrow separation is often the only form of eyebrow grooming among men. However, in some non-Western cultures this facial hair does not have a stigma, and may even be seen as a sign of feminine beauty, as in Caucasus or in Iran, where connected eyebrows are a sign of virginity and being unmarried.