au

Century Dictionary and Cyclopedia

1. n. A common English digraph representing generally the sound of “broad a” (â), but often also ä. It occurs only exceptionally, and by conformation with Romanic analogies, in words of Anglo-Saxon origin, as in aught, taught, daughter, haulm = halm, baulk = balk (and formerly as a variant, medially, with aw, as in baul, hauk, etc., for bawl, hawk, etc.). In words of Old French (and ultimately Latin) origin it represents an original al, now sometimes aul as in fault, assault, etc., or a before a nasal, as in aunt, haunch, launch, etc. (but in most such words now usually simplified to a, as in grand, grant, lance, etc.). It is frequently of Latin origin, as in audit, cause, laud, etc., or of Greek origin, as in caustic. In words from recent French it may have the present F. sound (ō) as in hauteur, au fait, etc. In words of German and usually of other foreign origin, it has its analytical value (ä + u), corresponding to English ou in sour, as in sauerkraut, ablaut, umlaut. Formerly au and aw were used almost indifferently; but now au is never final in English words, while aw is rarely medial, except in a few familiar words, as in hawk, bawl, but regularly final, as in law, saw, claw, etc. See aw.
2. n. To the; at the; with the: the dative of the French definite article, occurring in some phrases frequently used in English, as au fait, au fond, au revoir, etc.
3. n. The chemical symbol of gold (L., aurum).

WordNet 3.0

1. n. a soft yellow malleable ductile (trivalent and univalent) metallic element; occurs mainly as nuggets in rocks and alluvial deposits; does not react with most chemicals but is attacked by chlorine and aqua regia
2. n. a unit of length used for distances within the solar system; equal to the mean distance between the Earth and the Sun (approximately 93 million miles or 150 million kilometers)