terra - L., It. ‘earth’, as in terracotta unglazed pottery. XVII;. — It. ‘baked earth’ (cotta :- L. cocta, fem. pp. of coquere COOK); t. firma †mainland; dry land. XVII. — L., ‘firm land’ (fem. of firmus FIRM); t. incognita unexplored territory. XVII. — L., ‘unknown land’. terrae filius person of obscure parentage XVI; (Univ. of Oxford) formerly orator privileged to make humorous comments at a public act XVII. — L., ‘son of the earth’.

terra Latin, = ‘land’.
terra firma dry land; the ground as distinct from the sea or air. Recorded from the early 17th century, the phrase denoted originally the territories on the Italian mainland which were subject to the state of Venice.
terra incognita unknown or unexplored territory; the term is first recorded in John Smith's Description of New England (1616), in a reference to the supposed southern continent (Australia).

terra (pl. terrae) The term proposed by Galileo for the white, high-standing regions of the lunar surface, now generally referred to as the Lunar Highlands. These comprise the heavily cratered primary lunar felds-pathic crust, forming 83% of the lunar surface. The term is also used for extensive (continent-sized) elevated areas on planetary surfaces (e.g. Ishtar Terra on Venus).