ātmeti padaṃ śarīrendriyamanobuddhivedanāsaṃghātavyatiriktavacanaṃ prasiddhaparyāyavyatiriktatve satyekapadatvāt ghaṭādiśabdavat
The word "ātman" must denote something distinct from the aggregate of body, senses, mind, intellect and sensations, because while being different from [their] well-known synonyms, it is a single word, like the word "ghaṭa" etc.