"Feel keenly" is an expression used to describe an intense emotional response to something. There are several synonyms that can be used to convey a similar meaning, such as acutely, deeply, intensely, strongly, and profoundly. Each of these synonyms emphasizes a heightened sense of emotion, whether it be joy, sadness, anger, or regret. For instance, one might say they acutely felt the loss of a loved one or deeply felt the impact of a tragic event. Using synonyms for "feel keenly" can add depth and nuance to writing, conveying a range of emotions and intensities that allow for more specific and evocative language.