Other forms: earths
The earth is the planet we live on. On earth, the earth's surface, the earth moves.
It is capitalised as Earth when it is being named as one planet among others — Mars and Earth — and lower case in ordinary phrases like on earth. It also means soil: dig the earth, a mound of earth. In British electrical work, the earth is the safety connection to the ground, called the ground in America. Note down to earth, meaning practical and unpretentious; and what on earth, which is emphasis and not geography.
1nounearthThe planet we live on.
“The earth goes round the sun about once every three hundred and sixty-five days.”
2nounsoilSoil.
“Plant the seeds in the earth and water them every day.”
Too few real examples of this word to estimate which sense is commonest.
earth is a planet, or soil.
Old English eorthe is Germanic and comes from a root meaning ground or soil. The planet is named after dirt, which is true of the word in most European languages and is a useful corrective.
Middle English
erthe
English, today
earth
From Middle English erthe. From Middle English erthe, from Old English eorþe, from Proto-West Germanic erþu, from Proto-Germanic erþō (“dirt, ground, earth”), from Proto-Indo-European h₁er- (“earth”). 2
Etymology from Wiktionary, CC BY-SA