Terra-firma, a term frequently employed to denote continental land as distinguished from islands. But it was at one time more specially applied to all the mainland of Italy which acknowledged the supremacy of Venice, and to the northern part of South America. Colloquially, the phrase terra-firma is applied (but erroneously) to land as distinguished from water.
Terra-firma
Chambers's Encyclopaedia, Volume 10: Swastika to Zyrianovsk and Index, p. 143
Source scan(s): p. 0162