rational

adj

1. Capable of reasoning.

   “Man is a rational creature.”

   “The utility of valid arguments is a monument to our frailty: to the fact that we are not completely rational beings.”

2. Logically sound; not self-contradictory or otherwise absurd.

   “His statements were quite rational.”

   “Prevention for the future is now almost universally allowed to be the only rational plea for the infliction of punishment; but this, when left to the arbitrary discretion of individuals, always has been found, and always will be found, to degenerate into the exercise of revenge for the past.”

3. Healthy or balanced intellectually; exhibiting reasonableness.

   “rational conduct”

   “Temperature 99.8 degrees. Pulse 104. She was quite conscious and rational at times, at others very noisy.”

   “The [Isaac] Newton that emerges from the [unpublished] manuscripts is far from the popular image of a rational practitioner of cold and pure reason. The architect of modern science was himself not very modern. He was obsessed with alchemy.”

4. (not-comparable)Comprising, or expressible as, a ratio

   “¾ is a rational number, but √2 is an irrational number.”

5. (not-comparable)Comprising, or expressible as, a ratio
6. (not-comparable)Comprising, or expressible as, a ratio
7. (not-comparable)Comprising, or expressible as, a ratio
8. (not-comparable)Comprising, or expressible as, a ratio
9. (obsolete)synonymous replacement for "condensed" in condensed formula.

noun

1. A rational number: a number that can be expressed as the quotient of two integers.

   “The quotient of two rationals is again a rational.”

2. (historical)The breastplate worn by Israelite high priests.

   “The Rationale of iudgement alſo thou shalt mke with embrodered worke of diuers colours, according to the workmanship of the Ephod of gold, hyacinth, and purple, and ſcarlet twiſe died, and twiſted ſilke.”