Mantissa can mean:

• The "fraction part" (part after the separator) of the result of a logarithm. For this traditional use see common logarithm.
• The coefficient of floating-point numbers and numbers in scientific notation. For this more modern use, especially within the context of floating-point numbers, see significand.
• The "fraction part" (part after the separator) of the coefficient of floating-point numbers and normalized numbers in scientific notation. Also, see significand.
• The original (now archaic), non-mathematical meaning of mantissa is a "minor addition" or "supplement", e.g. to a text. It also sometimes meant "a worthless addition".

Mantissa can also refer to:

• Mantissa is also a novel by John Fowles.
• Mantissa is the name of a loose collection of ships which initially formed the base of the Yuhl/Goehl species/civilization in the Orphans of Earth Trilogy by Shawn Williams and Shane Dix.

Mathematical disambiguation Mantisse