The Collaborative International Dictionary
Mesologarithm
Mesologarithm \Mes`o*log"a*rithm\, n. [Meso- + logarithm : cf.
F. m['e]sologarithme.] (Math.)
A logarithm of the cosine or cotangent. [Obs.]
--Kepler.
Hutton.
Wiktionary
mesologarithm
n. (context mathematics obsolete English) A logarithm of the cosine or cotangent.