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.
The other classifications of numbers include: 1  Integers-similar to whole numbers, but they also include negative numbers. 2  Like natural and whole numbers, they do not have any fraction or decimal part. 3  Rational number-refers to the quotient of two integers with a nonzero denominator.