n. [ From L. valens, -entis, p. pr. of valere to have power, to be strong. See Valiant. ] (Chem.) The degree of combining power of an atom (or radical) as shown by the number of atoms of hydrogen (or of other monads, as chlorine, sodium, etc.) with which it will combine, or for which it can be substituted, or with which it can be compared; thus, an atom of hydrogen is a monad, and has a valence of one; the atoms of oxygen, nitrogen, and carbon are respectively dyads, triads, and tetrads, and have a valence respectively of two, three, and four. [ 1913 Webster ]

☞ The valence of certain elements varies in different compounds. Valence in degree may extend as high as seven or eight, as in the cases of iodine and osmium respectively. The doctrine of valence has been of fundamental importance in distinguishing the equivalence from the atomic weight, and is an essential factor in explaining the chemical structures of compounds. [ 1913 Webster ]

n. [ Perhaps fr. Valence in France. ] A kind of woven fabric for waistcoats, having the weft of wool and the warp of silk or cotton. [ Written also valentia. ] [ 1913 Webster ]

[ F.; -- so called after the town of Valenciennes. ] A rich kind of lace made at Valenciennes, in France. Each piece is made throughout, ground and pattern, by the same person and with the same thread, the pattern being worked in the net. [ 1913 Webster ]

n.; pl. Valencies (Chem.) (a) See Valence. (b) A unit of combining power; a so-called bond of affinity. [ 1913 Webster ]

n. See Valencia. [ 1913 Webster ]

n. 1. A sweetheart chosen on St. Valentine's Day. [ 1913 Webster ]

2. A letter containing professions of love, or a missive of a sentimental, comic, or burlesque character, sent on St. Valentine's Day. [ 1913 Webster ]

St. Valentine's Day, a day sacred to St. Valentine; the 14th of February. It was a very old notion, alluded to by Shakespeare, that on this day birds begin to mate. Hence, perhaps, arose the custom of sending love tokens at that time. [ 1913 Webster ]

n. (Eccl. Hist.) One of a school of Judaizing Gnostics in the second century; -- so called from Valentinus, the founder. [ 1913 Webster ]