A value in a set of numbers that has an equal probability of being selected from the total population of possibilities and, in that sense, is unpredictable. A random number is an instance of an unbiased random variable, that is, the output produced by a uniformly distributed random process. Random numbers may, e.g., be obtained by converting suitable stings of random bits (see [NIST SP 800-90A], Appendix B.5 for details).
Sources:
NIST SP 800-107 Rev. 1
under Random number
For the purposes of this Recommendation, a value in a set that has an equal probability of being selected from the total population of possibilities and, hence, is unpredictable. A random number is an instance of an unbiased random variable, that is, the output produced by a uniformly distributed random process.
Sources:
NIST SP 800-90A Rev. 1