Is the word trod a concrete noun or an abstract noun?

"Trod" is a verb, not a noun. It's the past tense of the verb "to tread."

Here's why it's not a noun:

* Concrete nouns refer to tangible, physical things you can touch (e.g., chair, book, water).

* Abstract nouns refer to ideas, concepts, qualities, or states of being (e.g., happiness, justice, love).

"Trod" describes an action, not a thing.