Here's why:
* Abstract nouns represent concepts, qualities, or ideas that cannot be touched or physically perceived.
* Meter as a unit of measurement: This is a concrete noun, as it refers to a specific unit of length. You can physically measure something in meters.
* Meter as rhythm in poetry: This is an abstract noun. It represents the rhythmic pattern of a poem, which is an idea or concept. You can't touch rhythm, you can only perceive it through the sound of the words.
Examples:
* Concrete: "The room is 5 meters long."
* Abstract: "The poet used a complex meter in the poem."
So, whether "meter" is abstract or concrete depends on how it's used in a sentence.