Definitions for "Random error"
Indefiniteness of result due to finite precision of experiment. Measure of fluctuation in result upon repeated experimentation.
An unsystematic error; a quantity (often indirectly observed) that appears to have no relationship with any other variable. Related to reliability and the standard error of measurement. American Educational Research Association, American Psychological Association, & National Council on Measurement in Education. (1999). Standards for educational and psychological testing. Washington, DC: American Educational Research Association, p. 180.
The difference between the actual and the desired quantity that varies randomly; that is, if a probability distribution of differences is produced, it is the Gaussian error function.