among metaphysicians, is taken in various senses. Sometimes it signifies a thing's not belonging to the essence of another; in which sense, the efficient cause and end of a thing are said to be extrinsic. Sometimes it signifies a thing's not being contained within the capacity of another; in which sense, those causes are called extrinsic which introduce something into a subject from without, as when a fire introduces heat. Sometimes it signifies a thing added, or applied, to another; in which sense accidents and adherents F, THE fourth consonant, and sixth letter of the alphabet. The letter F is borrowed from the digamma or double gamma of the Ælians, as is evident from the inscription on the pedestal of the Colossus at Delos; and was undoubtedly formed from the old Hebrew vau; and tho' this letter is not found in the modern Greek alphabet, yet it was in the ancient one, from whence the Latins received it, and transmitted it to us.

It is formed by a strong expression of the breath, and joining at the same time the upper-teeth and under-teeth. It has but one fort of sound, which has a great affinity with v and ph, the latter being written for it by us in all Greek words, as philosophy, &c. tho' the Italians write it filosofia.

The Romans for some time used an inverted F, Φ, instead of V consonant, which had no peculiar figure in their alphabet. Thus, in inscriptions we meet with TERMINAΦIT, DIΦI, &c. Lilius and others say, that it was the emperor Claudius who introduced the use of the inverted digamma, or Φ; but it did not long subsist after his death; for Quintilian observes, that it was not used in his time.

F, or φ, in music, is the fourth note in rising in this order of the gamut, ut, re, mi, fa. It likewise denotes one of the Greek keys in music, destined for the bass.

F, in physical prescriptions stands for Fiat, or "Let it be done." Thus f. s. a. signifies fiat secundum artem.

F was also a numeral letter, signifying 40; according to the verse,

Sexta quaterdenar gerit qua distat ab alpha.

And when a dash was added at top, thus f, it signified forty thousand.

F, in the civil law. Two fs joined together thus ff, signify the pandects. See Pandects.

F, in criminal law, a stigma or brand put upon felons with a hot iron, on their being admitted to the benefit of clergy; by stat. 4 H. 7. c. 13.