We don't have synonyms for mantissas yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are mantissa, mantispa and manassas.
(n) :
(mathematics, computing) The significand; that part of a floating-point number or number in scientific notation that contains its significant digits.
(n) :
(mathematics) The part of a common logarithm after the decimal point, the fractional part of a logarithm.
(n) :
(mathematics, computing) The significand; that part of a floating-point number or number in scientific notation that contains its significant digits.
(n) :
(mathematics) The part of a common logarithm after the decimal point, the fractional part of a logarithm.