expression, godan verb (-ru)
be deeply moved; get choked up; be overwhelmed with emotion
Describes a strong emotional surge that makes one's chest feel full, often to the point of tears. Used for both positive and negative overwhelming feelings.
See also: 胸一杯
卒業式で、胸がいっぱいになって言葉が出なかった。
At the graduation ceremony, I was so overwhelmed with emotion that I couldn't speak.
彼女の優しい手紙を読んで、胸がいっぱいになった。
Reading her kind letter, I felt a lump in my throat.