Exalith

Exalith is a term originally coined in the 23rd century to describe Ouranos Prime, and eventually the stargates, as they generally massed a few exatonnes - that is, a million, million, million metric tonnes. It existed as a counterpart of sorts to the term megastructure, but defined in terms of mass instead of size, and unambiguously implies a free-floating structure, not supported in any way.

The terms zettalith and yottalith are also sometimes used, specifying things of roughly Earth and Jupiter mass, respectively. While larger structures are possible, even the latter are considered to be colossal wastes of resources. Silverin is a moderate exception.