* Noun: When referring to the planet we live on, "earth" is a noun.
* Example: "The earth revolves around the sun."
* Noun: When referring to soil or dirt, "earth" is also a noun.
* Example: "The gardener added some earth to the flower bed."
* Adjective: When used as a modifier meaning "made of earth or clay", "earth" can function as an adjective.
* Example: "She wore an earth-toned dress."
To determine the part of speech, you need to consider how the word is being used in the sentence.