(used, esp. before a noun, with a specifying or particularizing effect, as opposed to the indefinite or generalizing force of the indefinite article a or an ): the book you gave me; Come into the house.
(used to mark a proper noun, natural phenomenon, ship, building, time, point of the compass, branch of endeavor, or field of study as something well-known or unique): the sun; the Alps; the Queen Elizabeth; the past; the West.
(used with or as part of a title): the Duke of Wellington; the Reverend John Smith.
(used to mark a noun as indicating the best-known, most approved, most important, most satisfying, etc.): the skiing center of the U.S.; If you're going to work hard, now is the time.
(used to mark a noun as being used generically): The dog is a quadruped.
(used in place of a possessive pronoun, to note a part of the body or a personal belonging): He won't be able to play football until the leg mends.
(used before adjectives that are used substantively, to note an individual, a class or number of individuals, or an abstract idea): to visit the sick; from the sublime to the ridiculous.
(used before a modifying adjective to specify or limit its modifying effect): He took the wrong road and drove miles out of his way.
(used to indicate one particular decade of a lifetime or of a century): the sixties; the gay nineties.
(one of many of a class or type, as of a manufactured item, as opposed to an individual one): Did you listen to the radio last night?
enough: He saved until he had the money for a new car. She didn't have the courage to leave.
12.(used distributively, to note any one separately) for, to, or in each; a or an: at one dollar the pound.