In speech ‘log’ pronounced “log” ‘log with a subscript x’ is pronounced ‘log base x’. If x is 10, you can shorten it and say ‘log ten’ ‘ln’ pronounced “natural log” or say the letters ‘l’ and ‘n’ quickly (ellen, emphasizing the first syllable) Usually the base is obvious from context and we say ‘log’ in those cases. It would be rare to routinely pronounce ‘logarithm’ because it’s too long.

I can’t remember a thing from math class, so I looked it up for you :) log: logarithm ln: natural logarithm lb: binary logarithm lg: common logarithm

Say it as it is, “logarithm”.