The phrase "under lonely" can be rephrased using a variety of synonyms. Instead of "lonely," one may use words such as "solitude," "isolation," or "desolation." To express a similar sentiment, one could also use less common terms such as "aloneness," "forlornness," or "seclusion." To further emphasize the feeling of being underneath or below something, one may use phrases like "submerged in solitude" or "beneath isolation." Regardless of the specific synonym chosen, the phrase "under lonely" paints a picture of isolation, emptiness, and perhaps even a sense of being trapped or buried beneath a weight of loneliness.