Strong's #107: 'iggereth (pronounced ig-eh'-reth)
 feminine of 104; an epistle:--letter.
Brown-Driver-Briggs Hebrew Lexicon:
 ּ 
  'iggereth 
 
 1) letter, missive
 
  Part of Speech: noun feminine
Relation: from H104
Usage:
This word is used 10 times:
2 Chronicles 30:1: "Israel and Judah, and wrote  letters also to Ephraim and Manasseh,"
2 Chronicles 30:6: "So the posts went  with the letters from the king and his princes throughout all"
Nehemiah 2:7: "If it please the king,  let letters be given the governors"
Nehemiah 2:8: " And a letter unto Asaph the keeper of the king's forest, that"
Nehemiah 2:9: "and gave them  letters. Now the king had sent captains of the army"
Nehemiah 6:5: "time with an open  letter in his hand;"
Nehemiah 6:17: "of Judah sent many  letters unto Tobiah, and the letters of Tobiah came"
Nehemiah 6:19: "me, and uttered my words to him. And Tobiah  letters to put me in fear."
Esther 9:26: "Therefore for all the words of this  letter, and of that which they had seen"
Esther 9:29: "this second  letter of Purim."