Iah is a god of the moon in ancient Eqyptian religion, and his name, jˁḥ (sometimes transliterated as Yah, Jah or Aah), simply means "moon." Nevertheless, by the New Kingdom he was less prominent as a moon deity than the other gods with lunar connections, Thoth and Khonsuah was also assimilated with Osiris, god of the dead, perhaps because, in its monthly cycle, the moon appears to renew itself. Iah also seems to have assumed the lunar aspect of Thoth, god of knowledge, writing and calculation; the segments of the moon were used as fractional symbols in writing.
. As a result of the functional connection between them he could be identified with either of those deities. Besides meaning moon his name can be interpreted as "Collar", "Embrace" and "Defender". His duties were shadowy and he was seen as a moon crescent often with a sun disk above it.
