إِيمَان
īmān
faith; belief
أـمـن
Most Arabic words are built from a small set of root letters — knowing the root helps you recognize related words across the dictionary.
الَّذِينَ آمَنُوا وَتَطْمَئِنُّ قُلُوبُهُم بِذِكْرِ اللَّهِ
Those who believed and whose hearts find rest in the remembrance of Allah (Quran 13:28)