log ‧ a ‧ rith ‧ m /ˈlɒɡərɪð ə m $ ˈlɒː-, ˈlɑː-/ BrE AmE noun [countable] technical
[ Date: 1600-1700 ; Language: Modern Latin ; Origin: logarithmus , from Greek logos ( ⇨ ↑ logic ) + arithmos 'number' ]
a number representing another number in a mathematical system so that complicated calculations can be done as simple addition