What is Iman literal meaning in english and use in Islam

The literal meaning of Iman is to believe in someone's words relying solely on his authority. 

In religious terms, it implies belief in the Unseen relying solely on the authority of the Messenger of Allah Subhanahu wa Ta'ala.

More Commonly term among Muslim scholar  is Aqeedah that is Synonymously used for Eemaan (Belief)
 (please dont go after terminology  .Without any question on word aqeedah which is right term but for your kind information it has not been used in quran and hadith,  Actually Emaan is the term that has been used in the Hadith of Jibraeel that articulate the islamic faith.......