reduce

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

• intransitive verb To bring down, as in extent, amount, or degree; diminish. synonym: decrease.
• intransitive verb To bring to a humbler, weaker, difficult, or forced state or condition; especially.
• intransitive verb To gain control of; subject or conquer.
• intransitive verb To subject to destruction.
• intransitive verb To bring to a specified undesirable state, as of weakness or helplessness.
• intransitive verb To compel to desperate acts.
• intransitive verb To lower in rank or grade; demote.
• intransitive verb To thicken or intensify the flavor of (a sauce, for example) by slow boiling.
• intransitive verb To lower the price of.
• intransitive verb To decrease the viscosity of (paint, for example), as by adding a solvent.
• intransitive verb To put in a simpler or more systematic form; simplify or codify.
• intransitive verb To turn into powder; pulverize.
• intransitive verb To decrease the valence of (an atom) by adding electrons.
• intransitive verb To remove oxygen from (a compound).
• intransitive verb To add hydrogen to (a compound).
• intransitive verb To change to a metallic state by removing nonmetallic constituents; smelt.
• intransitive verb Mathematics To simplify the form of (an expression, such as a fraction) without changing the value.
• intransitive verb Medicine To restore (a fractured or displaced body part) to a normal condition or position.
• intransitive verb Linguistics To pronounce (a stressed vowel) as the unstressed version of that vowel or as schwa.
• intransitive verb To become diminished.
• intransitive verb To lose weight, as by dieting.
• intransitive verb Biology To undergo meiosis.

from The Century Dictionary.

• To lead or bring back; restore; resolve to a former state.
• In surgery, to restore to its proper place, or so that the parts concerned are brought back to their normal topographical relations: as, to reduce a dislocation, fracture, or hernia.
• To bring to any specified state, condition, or form: as, to reduce civil affairs to order; to reduce a man to poverty or despair; to reduce glass to powder; to reduce a theory to practice; to reduce a Latin phrase to English.
• In metallurgy and chem., to bring into the metallic form; separate, as a metal, from the oxygen or other mineralizer with which it may be combined, or change from a higher to a lower degree of oxidation: as, to reduce the ores of silver or copper.
• To atone for; repair; redress.
• To bring down; diminish in length, breadth, thickness, size, quantity, value, or the like: as, to reduce expenses; to reduce the quantity of meat in diet; to reduce, the price of goods; to reduce the strength of spirit; to reduce a figure or design (to make a smaller copy of it without changing the form or proportion).
• To bring to an inferior condition; weaken; impoverish; lower; degrade; impair in fortune, dignity, or strength: as, the family were in reduced circumstances; the patient was much reduced by hemorrhage.
• To subdue, as by force of arms; bring into subjection; render submissive: as, to reduce mutineers to submission; Spain, Gaul, and Britain were reduced by the Roman arms.
• To bring into a class, order, genus, or species; bring within certain limits of definition or description.
• The variations of languages are reduced to rules.
• To show (a problem) to be merely a special case of one already solved.
• To change the denomination of (numbers): as, to reduce a number of shillings to farthings, or conversely (see reduction ); change the form of (an algebraic expression) to one simpler or more convenient.
• To prove the conclusion of (an indirect syllogism) from its premises by means of direct syllogism and immediate inference alone.
• To adjust (an observed quantity) by subtracting from it effects due to the special time and place of observation, especially, in astronomy, by removing the effects of refraction, parallax, aberration, precession, and nutation, changing a circummeridian to a meridian altitude, and the like.
• In Scots law, to set aside by an action at law; rescind or annul by legal means: as, to reduce a deed, writing, etc.
• Milit., to take off the establishment and strike off the pay-roll, as a regiment. When a regiment is reduced, the officers are generally put upon half-pay.
• Synonyms To lessen, decrease, abate, curtail, shorten, abridge, contract, retrench.
• Same as puer.

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

• transitive verb obsolete To bring or lead back to any former place or condition.
• transitive verb To bring to any inferior state, with respect to rank, size, quantity, quality, value, etc.; to diminish; to lower; to degrade; to impair.
• transitive verb To bring to terms; to humble; to conquer; to subdue; to capture.
• transitive verb To bring to a certain state or condition by grinding, pounding, kneading, rubbing, etc.
• transitive verb To bring into a certain order, arrangement, classification, etc.; to bring under rules or within certain limits of descriptions and terms adapted to use in computation
• transitive verb To change, as numbers, from one denomination into another without altering their value, or from one denomination into others of the same value
• transitive verb To change the form of a quantity or expression without altering its value
• transitive verb (Chem.), (Metallurgy), (Chem.) To add an electron to an atom or ion.