Az Zaahir

Ẓāhir is whatever shows — and the root also gives ẓahr, a back, the side of a thing you see when it turns away, and ẓuhr, the middle of the day, when nothing has a shadow to hide in.

It stands in the same ayah as al-Bāṭin, in the same breath, third of the four names in that ayah of Sūrat al-Ḥadīd. The ayah closes by saying He knows every thing. What is obvious and what is concealed are not two different subjects here; they are one sentence, said without a pause between them.