to bring down to a lower rank, dignity, etc.: a sergeant reduced to a corporal.

4.

to treat analytically, as a complex idea.

5.

to lower in price.

6.

to bring to a certain state, condition, arrangement, etc.:

to reduce glass to powder.

7.

to bring under control or authority.

8.

Cookery. to evaporate water from (a sauce, soup, or other liquid), usually by boiling.

9.

Photography. to lessen the density of (an exposed negative).

10.

to adjust or correct by making allowances, as an astronomical observation.

11.

Mathematics. to change the denomination or form, but not the value, of (a fraction, polynomial, etc.).

12.

Chemistry.

to add electrons to.

to deoxidize.

to add hydrogen to.

to change (a compound) so that the valence of the positive element is lower.

13.

Chemistry, Metallurgy. to bring into the metallic state by separating from nonmetallic constituents.

14.

to thin or dilute:

to reduce paint with oil or turpentine.

15.

to lower the alcoholic concentration of (spirits) by diluting with water.

16.

Surgery. to restore to the normal place, relation, or condition, as a fractured bone.

17.

Phonetics. to modify the quality of (a speech sound) to one of lesser distinctiveness, especially to pronounce (an unstressed vowel) as (ə) or another centralized vowel, as in the unstressed syllables of medicinal.

late 14c., "bring back," from Old French reducer (14c.), from Latin reducere "lead back, bring back," figuratively "restore, replace," from re- "back" (see re-) + ducere "bring, lead" (see duke (n.)). Meaning "bring to an inferior condition" is 1570s; that of "bring to a lower rank" is 1640s (military reduce to ranks is from 1802); that of "subdue by force of arms" is 1610s. Sense of "to lower, diminish, lessen" is from 1787. Related: Reduced; reducing.