* Adjective: Describing a surface, object, or something abstract.
* Example: "The table has a flat surface."
* Adverb: Modifying a verb, adjective, or another adverb, indicating lack of change or elevation.
* Example: "The car drove flat out."
* Noun: Referring to a flat surface, tire, or a flat drink.
* Example: "The roof is made of flat." "The car had a flat tire." "I ordered a flat white."
Therefore, to determine the part of speech, you need to look at the context of the sentence.