B1adjective
بَاطِنٌ
bāṭin
hidden / inward / esoteric
Example
هُوَ الْأَوَّلُ وَالْآخِرُ وَالظَّاهِرُ وَالْبَاطِنُ
huwa al-Awwalu wal-Ākhiru waẓ-Ẓāhiru wal-Bāṭin
He is the First and the Last, the Manifest and the Hidden (57:3)
Grammar
Active participle of بَطَنَ (to be hidden/inner). As divine name: الْبَاطِنُ (The Hidden). Noun: بَطْنٌ (interior/belly). Paired with ظَاهِرٌ.
Culture
The ẓāhir/bāṭin pair also applies to Quran interpretation — the apparent meaning and the deeper, hidden meaning.