A value that is chosen from a sample space is said to be biased if one value is more likely to be chosen than another value. Contrast with unbiased.
Sources:
NIST SP 800-90A Rev. 1
A value that is chosen from an alphabet space is said to be biased if one value is more likely to be chosen than another value. (Contrast with unbiased.)
Sources:
NIST SP 800-90B