What is the meaning of Mantissa?

A minor addition to a text.

The part of a common logarithm after the decimal point, the fractional part of a logarithm.

The significand; that part of a floating-point number or number in scientific notation that contains its significant digits.

mantissa (decimal part of a logarithm)

mantissa (part of a logarithm after the decimal point)

genitive/dative singular of mantin (“counsellor”)

mantissa (part of a logarithm after the decimal point)

Source: wiktionary.org