Real Dictionary

mumps
uncountable noun: Mumps is a disease usually caught by children. It causes a mild fever and painful swelling of the glands in the neck.

mumps in American English
an acute communicable disease, usually of childhood, caused by a paramyxovirus and characterized by swelling of the salivary glands, esp. the parotid, and, in adults, often complicated by inflammation of the testes, ovaries, etc.
noun: an infectious disease characterized by inflammatory swelling of the parotid and usually other salivary glands, and sometimes by inflammation of the testes or ovaries, caused by a paramyxovirus

mumps in British English
noun: an acute contagious viral disease of the parotid salivary glands, characterized by swelling of the affected parts, fever, and pain beneath the ear: usually affects children