Nymphs, in Greek Mythology, female divinities of inferior rank, inhabiting the sea, streams, groves, meadows and pastures, grottoes, fountains, hills, glens, and trees. Among them different classes were distinguished, particularly the Oceanides, daughters of Oceanus (nymphs of the great ocean which flows around the earth), the Nereids, daughters of Nereus (nymphs of the inner depths of the sea, or of the Inner Sea—the Mediterranean), Potameides (River nymphs), Naiads (nymphs of fountains, lakes, brooks, wells), Oréads (Mountain nymphs), Napææ (nymphs of glens), and Dryads or Hamadryads (Forest nymphs, who were believed to die with the trees in which they dwelt). They were the goddesses of the fertilising power of moisture, possessed prophetic power, and took interest in the nourishment and growth of infants, the chase, and dancing. They are among the most beautiful conceptions of the plastic fancy of the ancient Greeks. See Krause, Die Musen, Grazien, Horen und Nymphen (Halle, 1871).—For Nymph in natural history, see CHRYSALIS.

O

the fifteenth letter of our alphabet, is the only letter which cannot be traced to the Egyptian hieroglyphics. It is believed to have been an ideographic picture invented by the Semites to express a sound only found in Semitic languages. This supposition is supported by the correspondence of its Semitic name 'ayin, which means an 'eye,' with its oldest form $\backslash text\{O\}$, which may be regarded as the picture of an eye. The sound of 'ayin' was a faucal breath, resembling the h in huge. The Greeks, who took over the Phoenician alphabet, having no corresponding sound in their language, used the symbol for the vowels $\backslash acute\{o\}$, $\backslash acute\{ou\}$, and $\backslash acute\{ô\}$, which they required. In the earliest Greek inscriptions $\backslash text\{O\}$ represents all three sounds. About 550 B.C. the symbol was differentiated, the closed form $\backslash text\{o\}$, called omicron, or 'little o,' being appropriated for the short $\backslash acute\{o\}$, while it was opened out at the bottom, $\backslash text\{\Omega \}$, to represent the long $\backslash acute\{ô\}$, which was called omega or 'great o.' In the Italic alphabets, which were obtained from Greece before the invention of omega, only the first of these symbols appears, whereas in the Runes, which were obtained at a somewhat later date, the vowel o is expressed by a symbol derived from omega. In our English alphabet this letter has been more stable than any other. Its form is the same as that found on the Moabite stone, and its value agrees with its value in Greek and Latin, while it is the only English vowel which normally possesses the same sound which it has in French, German, and other modern continental languages. The sound is intermediate between a and u, and may arise out of either—i.e. it may represent an Anglo-Saxon a or u as well as an Anglo-Saxon o. In English it has three values: the name-sound heard in note, which is the original sound, the shorter sound heard in not, and the neutral vowel heard in son. In English the name-sound may be represented in ten ways, as in the words pole, goat, toe, yeoman, sow, sew, hautboy, beau, owe, and though.

Oahu. See HAWAII.