rationalize

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To make rational.
2. v. To interpret from a rational standpoint.
3. v. To devise self-satisfying but incorrect reasons for (one's behavior): "Many shoppers still rationalize luxury purchases as investments” ( Janice Castro).
4. v. Mathematics To remove radicals, such as from a denominator, without changing the value of (an expression) or roots of (an equation).
5. v. Chiefly British To bring modern, efficient methods to (an industry, for example).
6. v. To think in a rational or rationalistic way.
7. v. To devise self-satisfying but incorrect reasons for one's behavior.

Century Dictionary and Cyclopedia

1. To make conformable to reason; give rationality to; cause to be or to appear reasonable or intelligible.
2. To subject to the test of reason; explain or interpret by rational principles; treat in the manner of a rationalist; as, to rationalize religion or the Scriptures.
3. In algebra, to free from radical signs.
4. To think for one's self; employ the reason as a supreme test; argue or speculate upon the basis of rationality or rationalism; act as a rationalist.
5. Also spelled rationalise.

Wiktionary

1. v. To make something rational or more rational.
2. v. mathematics To remove radicals, without changing the value of an expression or the roots of an equation.
3. v. To structure something along modern, efficient and systematic lines, or according to scientific principles.

GNU Webster's 1913

1. v. To make rational; also, to convert to rationalism.
2. v. To interpret in the manner of a rationalist.
3. v. To form a rational conception of.
4. v. (Alg.) To render rational; to free from radical signs or quantities.
5. v. To use, and rely on, reason in forming a theory, belief, etc., especially in matters of religion: to accord with the principles of rationalism.

WordNet 3.0

1. v. think rationally; employ logic or reason
2. v. weed out unwanted or unnecessary things
3. v. defend, explain, clear away, or make excuses for by reasoning
4. v. remove irrational quantities from
5. v. structure and run according to rational or scientific principles in order to achieve desired results