All 4 Uses

rationalize
in
A Prayer for Owen Meany
(Edited)

And at another memorable moment, commenting on her son-in-law's affair with her daughter's 'greatest friend,' she rationalized: "If John is going to deceive Constance, it's nice it should be somebody we all know."
p. 110.2 *

rationalized = excused (as good or reasonable)
"It makes my job a lot easier, really," he rationalized.
p. 202.8
IF KENNEDY CAN RATIONALIZE.
p. 376.4

rationalize = think of a good excuse for
ADULTERY, WHAT ELSE CAN HE RATIONALIZE?
p. 376.4

Definitions:

(1) (rationalize as in: rationalize bad behavior)
to justify or explain behavior -- especially behavior that seems bad or unreasonable
(2) (meaning too rare to warrant focus)
More rarely today (though more common prior to the 20th century), rationalize can mean to think, or to make something reasonable, or to eliminate unreasonable aspects of something. Even more specifically (especially in Great Britain), rationalize can refer to re-structuring a company to be more efficient -- sometimes used as a euphemism for laying off employees (downsizing).

Rationalize also has a specialized definition in mathematics -- to eliminate irrational numbers from an equation or expression without changing its value.