Land mass was a large area of land, which was either surrounded by water or was contiguous with another land mass. It was a part of the total land mass (TLM).
The land mass of both Draygo IV and Vacca VI was listed in their planetary files. (TNG: "Homeward")
Cygnus IV was described as a yellowish ball with vague and indistinct land masses in the script for "Encounter at Farpoint".
Qo'noS was described as a planet with a single large land mass in the script for "Sins of The Father".
The Founders new homeworld was described as having no "discernible land mass" in the script for "Broken Link".