J
J, j, a consonant which, although originally represented by the same character as the vowel i, was distinguished from it by the ancients themselves, Charis. p. 1 P.; Diom. p. 416 ib.; Prisc. p. 544 ib.; Don. p. 1735 ib. al. The old grammarians supposed it to lengthen a preceding vowel (but v. Roby, Gram. 1, § 143). Its pronunciation was like that of the German j (or Engfish y) at the beginning of syllables, as jus, injuria, ejectus (Corss.). But where j occurs as a medial between two vowels, it is, according to the statement of the grammarians, to be pronounced double; wherefore, in such cases, it is also written double by many (e. g. by Cicero), as ajjo, Majja, ejjus, pejjus, etc., Quint. 1, 4, 11; Prisc. p. 545 P.; Vel. Long. p. 2219 ib. al.; and in inscriptions with a tall I. The closest relation exists between j and the vowel i, and in the course of formation and inflection they are very often interchanged: Pompejus, Pompei; Gajus, Gai; jam, etiam, quoniam; ajo, aibam. By the poets, i was often hardened into j to form position: abjete, abjetibus, for abiete, abietibus; cf. Val. Prob. p. 1432 P.; Mar. Vict. p. 2474 ib. J is related to g, as magis, major. J arises from dj or di, as Juppiter, Jovis, from Djuppiter, Djovis. J was omitted before another i in compounds of jacio with monosyllabic prepositions: abicit, adicit, obicit, for abjicit, adjicit, objicit. The preposition is regularly long (Verg. A. 6, 421), but after the time of Ovid is sometimes shortened (Luc. 9, 188). A diphthong is sometimes formed with the preceding vowel: r??cĕ (Verg. E. 3, 96), ??cĭt (Lucr. 3, 890). As an abbreviation, J. O. M. signifies Jovi Optimo Maximo; J. R. Juno Regina; J. V. T. Julia Victrix Togata.

Jana
Jana, ae, f., for Diana, the moon-goddess, Varr. R. R. 1, 37, 3; Macr. S. 1, 9; cf. the letter D. The goddess of doors and passages, Tert. adv. Nat. 2, 15.

Januarius
Jānŭārĭus, a, um, adj. id., of or belonging to Janus.
Esp., Januarius mensis, the month of January: auctio constituta in mensem Januarium, Cic. Agr. 1, 2, 4: Januario mense cura ut Romae sis, id. Att. 1, 2, 2.
Also, subst.: Jānŭārĭus, i, m. (sc. mensis), January: a. d. VII. Idus Januarii, Caes. B. C. 1, 5; Hirt. B. G. 8, 2. Kalendae Januariae, the first day of January. This was a festival on which the Romans presented their good wishes to each other It was also regarded as a fortunate day on which to begin any undertaking, Cic. Agr. 1, 8, 26; 2, 3, 6; 2, 3, 8; Ov. F. 1, 64; Col. 11, 2: Nonae Januariae, Caes. B. C. 3, 6; Plin. 8, 45, 70, § 177.

Janus
Jānus, i, m. root i, ire, prop. a going, a going through, passage; cf. janua, an old Italian deity. He was represented with a face on the front and another on the back of his head, Ov. F. 1, 245; hence, anceps, id. M. 14, 334. The month of January, Mensis Jani, Ov. F. 2, 51, was sacred to him, as were all other beginnings. The myth makes him a king of Latium or Etruria, where he hospitably received Saturn when expelled by Jupiter from Crete, Macr. S. 1, 7, 8, 9. He had a small temple in the Forum, with two doors opposite to each other, which in time of war stood open and in time of peace were shut; the temple was thrice closed on this account: in the time of Numa, after the first Punic war, and after the battle of Actium, Ov. F. 1, 281. With reference to his temple, the deity was called Janus geminus, or Janus Quirinus, Macr. S. 1, 9; Suet. Aug. 22; for which, poet.: Janus Quirini, Hor. C. 4, 15, 9.
Joined with pater: Januspater, Gell. 5, 12, 5. Transf. The temple of Janus: Janum ad infimum Argiletum indicem pacis bellique fecit, Liv. 1, 19; cf. Hor. Ep. 1, 20, 1. An arched passageway, covered passage, arcade: janos tres faciendos locavit, Liv. 41, 27; 2, 49; Cic. N. D. 2, 27, 67; Suet. Aug. 31. In partic., Jani, four arched passages in the Roman Forum, where the merchants and moneychangers had their stand: qui Puteal Janumque timet, celeresque Calendas, Ov. R. Am. 561: haec Janus summus ab imo Prodocet, Hor. Ep. 1, 1, 54: postquam omnis res mea Janum Ad medium fracta est, id. S. 2, 3, 18; Cic. Off. 2, 25, 90; id. Phil. 6, 5, 15 al. A year: vive, vale et totidem venturos congere Janos, quot, etc., Aus. Ep. 20, 13.