Q, or q, the 16th letter and 12th consonant of our alphabet; but is not to be found either in the Greek, old Latin, or Saxon alphabets; and indeed some would entirely exclude it, pretending that k ought to be used wherever this occurs. However, as it is formed in the voice in a different manner, it is undoubtedly a distinct letter: for, in expressing this sound, the cheeks are contracted, and the lips, particularly the under one, are put into a canular form, for the passage of the breath.
The q is never sounded alone, but in conjunction with u, as in quality, question, quite, quote, &c. and never ends any English word.
As a numeral, Q stands for 500; and with a dash over it, thus , for 500,000.
Used as an abbreviation q signifies quantity, or quantum. Thus, among physicians, q. pl. is quantum placet, i. e. "as much as you please" of a thing; and q. f. is quantum sufficit, i. e. "as much as is necessary." Q. E. D. among mathematicians, is quod erat demonstrandum, i. e. "which was to be demonstrated;" and Q. E. F. is quod erat faciendum, i. e. "which was to be done." Q. D. among grammarians is quasi dictum, i. e. "as if it were said;" or, "as who should say." In the notes of the ancients, Q stands for Quintus, or Quintius; Q. B. V. for quod bene vertat; Q. S. S. S. for quæ supra scripta sunt; Q. M. for Quintus Mutius, or quomodo; Quint. for Quintilius; and Quæst. for quæstio.