The name for NH4+ is Ammonium.
Ammonium is a positively charged polyatomic ion formed when ammonia (NH3) accepts a proton (H+). In chemistry, NH4+ is commonly encountered in various compounds, especially in fertilizers, where it plays a crucial role in providing nitrogen required for plant growth. The presence of ammonium ions in a solution can contribute to the acidity and influence the behavior of other ions in the solution.