“ATMA” word is a Noun OR Pronoun
It is a noun. The root word is ‘आत्मन्’. The word आत्मा is singular nominative case (कर्त्ता कारक, एकवचन)
I think it should be pronoun as we can use it in place of “I” or “swayam”.
The Sanskrit word for ‘I’ is अहम् (singular nominative case). The root word is अस्मद्. And स्वयं itself is a Sanskrit word. The word आत्मन् means soul.
I stand corrected - the word आत्मन् can also be used as a pronoun…