- 16th letter of the classical Roman alphabet, from the Phoenician equivalent of Hebrew koph, which was used for the more guttural of the two "k" sounds in Semitic.
The letter existed in Greek, but was little used and not alphabetized; the stereotypical connection with -u- began in Latin. Anglo-Saxon scribes adopted the habit at first, but later used spellings with cw- or cu-. The qu- pattern returned to English with the Norman Conquest. Scholars use -q- alone to transliterate Semitic koph (e.g. Quran, Qatar, Iraq ).
In Christian theology, Q has been used since 1901 to signify the hypothetical source of passages shared by Matthew and Luke, but not in Mark; probably it is an abbreviation of German Quelle "source."