Question

what is word earth refers to ?

Answer 1

In general English usage, the name Earth can be capitalized or spelled in lowercase
interchangeably, either when used absolutely or prefixed with "the" (i.e. "Earth", "the Earth",
"earth" or "the earth"). Many deliberately spell the name of the planet with a capital, both as
"Earth" or "the Earth". This is to distinguish it as a proper noun, distinct from the senses of the
term as a count noun or verb (e.g. referring to soil, the ground, earthing in the electrical sense,
etc.). Oxford spelling recognizes the lowercase form as the most common, with the capitalized
form as a variant of it. Another convention that is very common is to spell the name with a capital
when occurring absolutely (e.g. Earth's atmosphere) and lowercase when preceded by "the" (e.g.
the atmosphere of the earth). The term almost exclusively exists in lowercase when appearing in
common phrases, even without "the" preceding it (e.g. it does not cost the earth; what on earth are
you doing?).[1]
Terms that refer to the Earth can use the Latin root terr-, as in terraform and terrestrial. An
alternative Latin root is tellur-, which is used in words such as tellurian and tellurium. Such terms
derive from Latin terra and tellus, which refer variously to the world, the element earth, the earth
goddess and so forth.[1]
Scientific terms such as geography, geocentric, and geothermal use the
Greek prefix geo