re·duce / riˈd(y)oōs/ • v. [tr.] 1. make smaller or less in amount, degree, or size: the need for businesses to reduce costs the workforce has been reduced to some 6,100| [as adj.] (reduced) a reduced risk of coronary disease. ∎  [intr.] become smaller or less in size, amount, or degree: the number of priority homeless cases has reduced slightly. ∎  boil (a sauce or other liquid) in cooking so that it becomes thicker and more concentrated. ∎  [intr.] (of a person) lose weight, typically by dieting: by May she had reduced to 125 pounds. ∎ archaic conquer (a place), in particular besiege and capture (a town or fortress). ∎  Photog. make (a negative or print) less dense. ∎  Phonet. articulate (a speech sound) in a way requiring less muscular effort. In vowels, this gives rise to a more central articulatory position.2. (reduce someone/something to) bring someone or something to (a lower or weaker state, condition, or role): she has been reduced to near poverty the church was reduced to rubble. ∎  (be reduced to doing something) (of a person) be forced by difficult circumstances into doing something desperate: ordinary soldiers are reduced to begging. ∎  make someone helpless with (an expression of emotion, esp. with hurt, shock, or amusement): Olga was reduced to stunned silence. ∎  force into (obedience or submission): he succeeds in reducing his grandees to due obedience.3. (reduce something to) change a substance to (a different or more basic form): it is difficult to understand how lava could have been reduced to dust. ∎  present a problem or subject in (a simplified form): he reduces unimaginable statistics to manageable proportions. ∎  convert a fraction to (the form with the lowest terms).4. Chem. cause to combine chemically with hydrogen. ∎  undergo or cause to undergo a reaction in which electrons are gained by one atom from another. The opposite of oxidize.5. restore (a dislocated part) to its proper position by manipulation or surgery. ∎  remedy (a dislocation) in such a way.PHRASES: reduced circumstances used euphemistically to refer to the state of being poor after being relatively wealthy: a divorcee living in reduced circumstances.reduce someone to the ranks demote a noncommissioned officer to an ordinary soldier.DERIVATIVES: re·duc·er n.ORIGIN: late Middle English: from Latin reducere, from re- ‘back, again’ + ducere ‘bring, lead.’ The original sense was ‘bring back’ (hence ‘restore,’ now surviving in sense 5); this led to ‘bring to a different state,’ then ‘bring to a simpler or lower state’ (hence sense 3); and finally ‘diminish in size or amount’ (sense 1, dating from the late 18th cent.).

reduce †bring or lead back XIV; bring or restore to a condition; bring into subjection, bring down XV; diminish XVI. — L. redūcere bring back, restore, replace, f. RE- + dūcere lead, bring.
So reduction XV. — (O)F. or L.

reduce The process of boiling a mixture (especially when making a sauce, soup, or syrup) in an uncovered pan to evaporate surplus liquid and give a more concentrated product.