User blog comment:Roranoa Drake II/Episode 725 Review: Road to Gear Fourth/@comment-24850639-20160111190801/@comment-5398287-20160112000618

Taking the quote from cnet, aka best translator:

Zoro: Vvvvhhhh...!! Nine mountain ranges and eight oceans... // ...form one world......!! // A thousand worlds form a Small Thousandfold World......!! Raise to the power of three... // ...and there is nothing I cannot cleave.

And his translation note for Daisen Sekai:

[TN: “One-Great Thrice-Thousandfold Great-Thousandfold World” - based on the Buddhist concept of a universe that is made of 1000 times 1000 times 1000 worlds.]

So the Triliochosm or whatever it was that the subs used is a way of conveying the number of worlds that Zoro is talking about. As for how it relates to the technique, well...maybe because the cut is so much more powerful than, say, the 1080 Pound Cannon or whatever?

(source)