There are a few ways to render the word. Εβδομ?δα,Evdomada , Εβδομ??,Evdomas, Επτα?μερο, Eptaimero, Επτ?μερο, Eptamero. or Εφτ?μερο, Eftamero.

The 3 last words come from the combination of the words Epta or Efta which is the Number 7, and the word Mera which means day and in the combination becomes "mero" signifying the whole period and not a single day.

It's "εβδομ?δα".

http://www.forvo.com/word/εβδομ?δα

According to Google translate: εβδομ?δα, evdomáda

evthomatha