To reduce in quality or purity.
To reduce in altitude or magnitude, as hills and mountains; to wear down.
To lower in value or social position.
To bring down the size, quantity, quality, value or intensity of something; to diminish, to lower.
To annul by legal means.
To convert to written form. (Usage note: this verb almost always appears as "reduce to writing".)
To lose weight.
To perform a reduction; to restore a fracture or dislocation to the correct alignment.
To bring to an inferior state or condition.
To simplify an equation or formula without changing its value.
To bring to an inferior rank; to degrade, to demote.
To convert a syllogism to a clearer or simpler form.
To add electrons / hydrogen or to remove oxygen.
To humble; to conquer; to subdue; to capture.
To strike off the payroll.
To decrease the liquid content of food by boiling much of its water off.
To produce metal from ore by removing nonmetallic elements in a smelter.
To express the solution of a problem in terms of another (known) algorithm.
To reform a line or column from (a square).