Definition/Meaning  Word/Phrase 
number of which a given number is the logarithm 
antilog
,
antilogarithm

integer part (positive or negative) of the representation of a logarithm; in the expression log 643 
characteristic

logarithm integer part 
characteristic

logarithm to the base 10 
common logarithm

logarithmic unit of sound intensity; 10 times the logarithm of the ratio of the sound intensity to some reference intensity 
dB
,
decibel

(psychophysics) the concept that the magnitude of a subjective sensation increases proportional to the logarithm of the stimulus intensity; based on early work by E. H. Weber 
Fechner's law
,
WeberFechner law

positive fractional part of the representation of a logarithm; in the expression log 643 
fixedpoint part
,
mantissa

logarithm decimal part 
mantissa

logarithm to the base e 
Napierian logarithm
,
natural logarithm

(from potential of Hydrogen) the logarithm of the reciprocal of hydrogenion concentration in gram atoms per liter; provides a measure on a scale from 0 to 14 of the acidity or alkalinity of a solution (where 7 is neutral and greater than 7 is more basic 
pH
,
pH scale
