The Collaborative International Dictionary of English v.0.48:

landmass \landmass\ n.
   a large continuous extent of land; as, the Eurasian landmass.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

landmass
    n 1: a large continuous extent of land [syn: landmass, land
         mass]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "landmass":
   Africa, America, Antarctica, Antipodes, Asia, Asia Major,
   Asia Minor, Australasia, Australia, East, Eastern Hemisphere,
   Eurasia, Eurasian landmass, Europe, Far East, Levant, Middle East,
   Near East, New World, North America, Occident, Oceania, Old World,
   Orient, South America, West, Western Hemisphere, continent,
   down under, eastland, main, mainland, peninsula, subcontinent,
   the old country