Definition of lumbar puncture. : puncture of the subarachnoid space in the lumbar region of the spinal cord to withdraw cerebrospinal fluid or inject anesthetic drugs.
Rational Numbers A rational number is a number that can be written as a ratio. That means it can be written as a fraction, in which both the numerator (the number on top) and the denominator (the number on the bottom) are whole numbers. The number 8 is a rational number because it can be written as the fraction 8/1.
Real Numbers. In math, the real numbers contains both rational numbers and irrational numbers. The rational number is in the form of $\frac{5}{3}$, $\frac{-23}{40}$. And the irrational numbers like pi, $\sqrt 2$, any number in decimal representation like 2.4873.... where the digit is continuing in the way.