The phrase "particular index" refers to a specific list or system that helps organize and locate information. It is used to denote a specific and precise index, rather than a general or random one. Full definition
So I'm just basically mirroring that particular index by buying the exchange - traded fund, in real layman's terms. (purefinancial.com)
The bottom line is that variable interest rates rise or fall in direct proportion to the behavior of a particular index. (thesimpledollar.com)
A portfolio that's relatively independent of the overall market, and that doesn't attempt to beat a particular index, is recommended. (gobankingrates.com)