The Sumerian word NIN (Akkadian pronunciation of the sign: EREŠ) can denote a queen or a priestess, and is often translated "lady". (Other translations: - queen, mistress, proprietress, lady; lord.)
The NIN sign is written as MUNUS.TÚG 𒊩𒌆 in archaic cuneiform (as well as in the Codex Hammurabi), the syllable nin on the other hand is spelled as MUNUS.KA 𒊩𒅗 in Assyrian cuneiform. MUNUS.KU = NIN9 𒊩𒆪 has the reading "sister".
NIN in the Gilgamesh epic 
Ninsun-(DNIN.SÚN) as the mother of Gilgamesh in the Epic of Gilgamesh-(Standard Babylonian version), appears in 5 of the 12 Chapters (Tablets I, II, III, IV, XII). The other personage using 'NIN' is the god Ninurta-(DNIN.URTA) who appears in Tablet I, and especially the Flood myth of Tablet XI.
Of the 51 uses of the 'nin' (cuneiform), the other major usage is for the Akkadian word eninna–("nin" as in e-nin-na, but also other variants). Eninna is the adverb "Now", but is also conjunctionally-used, or as a segue-form, (a transition form).
The two uses of 'NIN' as the word for 'sister'-(Akk. ahātu), for example is used in Tablet 8 (The Mourning of Enkidu), line 38:
- "May ...
- "May the brothers go into mourning over you like sisters;"
See also 
- Parpola, Simo, with Mikko Luuko, and Kalle Fabritius (1997). The Standard Babylonian, Epic of Gilgamesh. The Neo-Assyrian Text Corpus Project. ISBN 951-45-7760-4 (Volume 1) in the original Akkadian cuneiform and transliteration; commentary and glossary are in English Check