1. the state or quality of being rational.
2. the possession of reason.
3. agreeableness to reason; reasonableness.
4. the exercise of reason.
5. a reasonable view, practice, etc.
There's a lot of reference to reason there. But let's look at rational, first.
1. agreeable to reason; reasonable; sensible: a rational plan for economic development.
2. having or exercising reason, sound judgment, or good sense: a calm and rational negotiator.
3. being in or characterized by full possession of one's reason; sane; lucid: The patient appeared perfectly rational.
4. endowed with the faculty of reason: rational beings.
5. of, pertaining to, or constituting reasoning powers: the rational faculty.
6. proceeding or derived from reason or based on reasoning: a rational explanation.
All about reason again. So we have to get around to the definition of reason.
1. a basis or cause, as for some belief, action, fact, event, etc.: the reason for declaring war.
2. a statement presented in justification or explanation of a belief or action.
3. the mental powers concerned with forming conclusions, judgments, or inferences.
4. sound judgment; good sense.
5. normal or sound powers of mind; sanity.
6. Logic. a premise of an argument.
a. the faculty or power of acquiring intellectual knowledge, either by direct understanding of first principles or by argument.
b. the power of intelligent and dispassionate thought, or of conduct influenced by such thought.
c. Kantianism. the faculty by which the ideas of pure reason are created.
Except for philosophical definitions A and B, they all simply describe the process of Judgement without having a bias toward Think or against Feeling. There you go, the majority of definitions do not discount Feeling, and one definition would have been good enough.
BlueWing, I have just answered your entire thread. We can see that there is justifcation in Jung using the phrase "rational".