Ideal Random Sequence definition in Computer Security terms:
Definition(s): Each bit of an ideal random sequence is unpredictable and unbiased, with a value that is independent of the values of the other bits in the sequence. Prior to the observation of the sequence, the value of each bit is equally likely to be 0 or 1, and the probability that a particular bit will have a particular value is unaffected by knowledge of the values of any or all of the other bits. An ideal random sequence of n bits contains n bits of entropy.
Source(s): NIST SP 800-90A Rev. 1
reference: CSRC Glossary