The verb reduce has 19 senses (first 11 from tagged texts)
1. (103) reduce, cut down, cut back, trim, trim down, trim back, cut, bring down -- (cut down on; make a reduction in; "reduce your daily fat intake"; "The employer wants to cut back health benefits")
2. (11) reduce -- (make less complex; "reduce a problem to a single question")
3. (5) reduce -- (bring to humbler or weaker state or condition; "He reduced the population to slavery")
4. (3) reduce -- (simplify the form of a mathematical equation of expression by substituting one term for another)
5. (3) reduce -- (lower in grade or rank or force somebody into an undignified situation; "She reduced her niece to a servant")
6. (3) reduce, come down, boil down -- (be the essential element; "The proposal boils down to a compromise")
7. (2) shrink, reduce -- (reduce in size; reduce physically; "Hot water will shrink the sweater"; "Can you shrink this image?")
8. (1) reduce -- (lessen and make more modest; "reduce one's standard of living")
9. (1) reduce, scale down -- (make smaller; "reduce an image")
10. (1) deoxidize, deoxidise, reduce -- (to remove oxygen from a compound, or cause to react with hydrogen or form a hydride, or to undergo an increase in the number of electrons)
11. (1) reduce, tighten -- (narrow or limit; "reduce the influx of foreigners")
12. repress, quash, keep down, subdue, subjugate, reduce -- (put down by force or intimidation; "The government quashes any attempt of an uprising"; "China keeps down her dissidents very efficiently"; "The rich landowners subjugated the peasants working the land")
13. reduce -- (undergo meiosis; "The cells reduce")
14. reduce -- (reposition (a broken bone after surgery) back to its normal site)
15. abridge, foreshorten, abbreviate, shorten, cut, contract, reduce -- (reduce in scope while retaining essential elements; "The manuscript must be shortened")
16. boil down, reduce, decoct, concentrate -- (be cooked until very little liquid is left; "The sauce should reduce to one cup")
17. reduce, boil down, concentrate -- (cook until very little liquid is left; "The cook reduced the sauce by boiling it for a long time")
18. dilute, thin, thin out, reduce, cut -- (lessen the strength or flavor of a solution or mixture; "cut bourbon")
19. reduce, melt off, lose weight, slim, slenderize, thin, slim down -- (take off weight)