mantissa

noun

Etymology: Borrowed from Latin mantissa, mantīsa, of unknown origin (said by Festus to be a loanword from Etruscan, but it may actually be from Celtic, possibly through Etruscan mediation).

1. A minor addition to a text.
2. The part of a common logarithm after the decimal point, the fractional part of a logarithm.
3. The significand; that part of a floating-point number or number in scientific notation that contains its significant digits.