natural logarithmnatural logarithm
a logarithm to the base e
A logarithm in which the base is the irrational number e (= 2.71828 … ). For example, ln 10 = log e 10 = approximately 2.30258. Also called Napierian logarithm .
(plural natural logarithms)
From New Latin log naturalis, coined in 1668 by Nicholas Mercator in his book Logarithmo-technica.