Cannonball by Supertramp is a reflective track from their album 'Brother Where You Bound.' The song delves into themes of regret, love, and the passage of time. The lyrics narrate a story of a failed relationship, portraying the pain and sorrow that accompany lost love. The 'Cannonball' metaphor signifies the powerful impact of these emotions on the protagonist. Key themes include introspection, unrequited love, and emotional turmoil. Particularly poignant moments in the song arise when the lyrics speak directly to the heartache of realizing that love has slipped away, emphasizing the intensity of the emotional 'cannonball' that hits the narrator.