OASIS. A fertile spot in the midst of a sandy desert.

OATH. A solemn affirmation or denial of anything, before a person authorized to administer the same, for discovery of truth and right. (See [Corporal Oath].) Hesiod ascribes the invention of oaths to discord. The oath of supremacy and of the Protestant faith was formerly taken by an officer before he could hold a commission in the royal navy.

OAZE. Synonymous with the Ang.-Sax. wase when applied to mud. (See [Ooze].)

OBEY. A word forming the fulcrum of naval discipline.

OBI. A horrible sorcery practised among the negroes in the West Indies, the infliction of which by a threat from the juggler is sufficient to lead the denounced victim to mental disease, despondency, and death. Still the wretched trash gathered together for the obi-spell is not more ridiculous than the amulets of civilized Europe.

OBLATE. Compressed or flattened.

OBLIGATION. A bond containing a penalty, with a condition annexed for payment of money or performance of covenants.

OBLIMATION. The deposit of mud and silt by water.

OBLIQUE-ANGLED TRIANGLE. Any other than a right-angled triangle.

OBLIQUE ASCENSION. An arc between the first point of Aries and that point of the equator which comes to the horizon with a star, or other heavenly body, reckoned according to the order of signs. It is the sum or difference of the right ascension and ascensional difference.