What is the Irish word for Ireland?

Eire

http://www.ibiblio.org/gaelic/Eire/eire.html

There are two poetic names of Innisfail and Erin.

Innisfail, English translation: Irish for "Island of Destiny" but as a proper noun, it doesn't necessarily need to be translated.

The ancient names of Ireland, according to various historians are as follows: Orpheus of Crotona 543 BC calls it Ierna Invenal: Pomponius Mela Solonius called the island Inverna: Ptolemy, Iris: Diodorus Siculus, Iren: Plutach, Ogygia: Claudianus, Strabo: Stephen of Byzantium, Ierne: Rufus Festus Avienus, Insula Sacra: Caesar and most Latin historians called it Hibernia. Scotia was another ancient name as was Innisfail, the island of Destiny. The English gave it the name of Ireland, The "land of ire".

https://books.google.com/books?id=DZfDb_Mfqv8C&pg=PA13&lpg=PA13&dq=The+ancient+names+of+Ireland,+according+to+various+historians+are+as+follows&source=bl&ots=w6xn0YOLBH&sig=EJKKqtkJ4gVi5ArVLIIfP7ArQrE&hl=en&sa=X&ved=0ahUKEwiwsYzju97OAhUEwiYKHQX0BJwQ6AEIGzAB#v=onepage&q=The%20ancient%20names%20of%20Ireland%2C%20according%20to%20various%20historians%20are%20as%20follows&f=false

http://tinyurl.com/zugdwty

Ireland has lots of poetic names, such as Banba or Fodhla, but the official name in Irish is Eire. This has another form, Eireann, which is often written Erin in English, so Eire and Erin are really the same name.

Erin is a Hiberno-English derivative of Irish Gaelic Éirinn, the dative case - and also locative case - of Éire, the Irish word for "Ireland". Poets and also nineteenth-century Irish nationalists also used Erin in English as a romantic name for Ireland, as shown in the catchphrase (when speaking of Ireland's experiences with Britain), "Let Erin Remember".
http://www.answers.com/topic/erin

A poetic name for Ireland was Roisin Dubh.

Róisín Dubh, meaning "Black Rose", written in the 16th century, is one of Ireland's most famous political songs. It is based on an older love-lyric in which referred to the poet's beloved rather than, as here, being a metaphor for Ireland. The intimate tone of the original carries over into the political song. It is often attributed to Antoine Ó Raifteiri, but almost certainly predates him. Originally translated from the Irish language by James Clarence Mangan.

The song is named after Róisín Dubh, probably one of the daughters of Hugh O'Neill, 2nd Earl of Tyrone, Earl of Tyrone in the late 16th Century. The song is reputed to have originated in the camps of Red Hugh O'Donnell.
https://en.wikipedia.org/wiki/R%C3%B3is%C3%ADn_Dubh_%28song%29

Éire or Erin is the name for Ireland in Irish

Éire was the State name from 1937-1948.