Sentence:  Luckily, even though the arithmetic <WSD>mean</WSD> is unusable, both the harmonic and geometric <WSD>means</WSD> settle to precise values as the amount of data increases. 
Meaning of the word marked with <WSD> tags:  Any function of multiple variables that satisfies certain properties and yields a number representative of its arguments; or, the number so yielded; a measure of central tendency.