braille
n. a system of letters, numbers, punctuation marks, and scientific and musical symbols adapted as a written language for people with severe visual impairment, using combinations of raised dots that can be touched. Each character comprises a specific pattern of six dots organized in two parallel vertical columns. Prefix symbols are used to indicate capitalization and numbers, and various other conventions are used to represent more than 200 common words or recurring letter combinations. [introduced in 1829 by Louis Braille (1809–1852), French teacher and inventor]