the

from The American Heritage® Dictionary of the English Language, 5th Edition.

• definite article. Used before singular or plural nouns and noun phrases that denote particular, specified persons or things.
• definite article. Used before a noun, and generally stressed, to emphasize one of a group or type as the most outstanding or prominent.
• definite article. Used to indicate uniqueness.
• definite article. Used before nouns that designate natural phenomena or points of the compass.
• definite article. Used as the equivalent of a possessive adjective before names of some parts of the body.
• definite article. Used before a noun specifying a field of endeavor.
• definite article. Used before a proper name, as of a monument or ship.
• definite article. Used before the plural form of a numeral denoting a specific decade of a century or of a lifespan.
• definite article. Used before a singular noun indicating that the noun is generic.
• definite article. Used before an adjective extending it to signify a class and giving it the function of a noun.
• definite article. Used before an absolute adjective.
• definite article. Used before a present participle, signifying the action in the abstract.
• definite article. Used before a noun with the force of per.
• adverb To that extent; by that much. Used before a comparative.
• adverb Beyond any other.

from The Century Dictionary.

• See thee.
• Used to modify adjectives and adverbs in the comparative degree:
• Used without correlation, it signifies in any degree; in some degree: as, Are you well ? The better for seeing you.
• A Middle English form of though.
• noun A Middle English form of thigh.
• A word used before nouns with a specifying or particularizing effect, opposed to the indefinite or generalizing force of a or an: as, the gods are careless of mankind; the sun in heaven; the day is fair; long live the king!
• A word used before a noun to indicate a species or genus: as, the song of the nightingale: used in generalization: as, the man that hath no music in himself.
• A word used with a title, or as part of a title: as, the Duke of Wellington; the Right Honorable the Earl of Derby; the Lord Brook; the Reverend John Smith.
• Indicating the most approved, most desirable, most conspicuous, or most important of its kind: as, Newport is the watering-place of the United States: in this use emphatic, and frequently italicized. The is often placed before a person's (especially a woman's) name, to indicate admiration or notoriety (a colloquial use): as, the Elssler.
• Before adjectives used substantively, denoting: An individual: as, she gazed long on the face of the dead.
• A class, or a number of individuals: as, the good die first; do not mix the new with the old.
• An abstract notion: as, the beautiful.
• Denoting that which is well known or famed: as, the prodigal son.
• Used distributively to denote any one separately: as, the fare is a dollar the round trip.
• Used in place of the possessive pronoun to denote a personal belonging: as, to hang the head and weep.
• Used to denote a particular day in relation to a given week, or to some other day of the same Week.
• Used before a participial infinitive, or gerund, followed by an object: the article is now omitted in this construction.
• Used before the relative which: now an archaism.
• [The is generally pronounced as if a syllable (unaccented) of the following word (a proclitic), and its vowel is accordingly obscured, before a consonant, into the neutral vowel-sound of her or but, very lightly sounded (quite like the French “mute e”); before a vowel, often in the same manner, but more usually with the short i sound of pin, only less distinct; when emphatic, as the long e of thee. In poetry, before a word beginning with a vowel-sound, the vowel of the generally may slide into that of the next word, and form with it one metrical syllable; metrically the e is accordingly often cut off in printing. The same so-called elision (synalephe) often took place in Middle English, the being written with the following noun as one word: as, themperour, the emperor.
• In Middle English manuscripts the was often written, as in Anglo-Saxon þe, with the character þ; in early print this character was represented by a form nearly like y, and later printers actually used y instead, þe, erroneously printed þ^e as if contracted, like þ^t for that, being printed ye or y^e but always pronounced, of course, the. Modern archaists often affect ye for the, and many pronounce it as it looks, “yē.”

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb obsolete See thee.
• A word placed before nouns to limit or individualize their meaning.
• adverb By that; by how much; by so much; on that account; -- used before comparatives.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adverb With a comparative or more and a verb phrase, establishes a parallel with one or more other such comparatives.
• adverb this sense) With a comparative, and often with for it, indicates a result more like said comparative. This can be negated with none.