The phrase "dumb with grief" is often used to describe the overwhelming feeling of sorrow that can render someone speechless. However, there are a variety of synonyms that can convey a similar sentiment. "Heartbroken" or "crushed" are among the frequently used synonyms for this phrase. "Despondent" and "melancholic" are also excellent synonyms that describe a state of deep sadness, without necessarily implying a lack of communication. Additionally, "numb with sadness" or "bereaved" could be suitable alternatives. Ultimately, the most important thing is to choose a synonym that accurately reflects the intensity of the sorrow being experienced.