The phrase "by one's self" means alone, independent, or without the help or presence of others. There are many synonyms for this phrase, including "solo," "unaided," "independently," "solitary," "lonely," "single-handed," "without assistance," and "singly." These words all convey the idea of being alone, whether by choice or circumstance, and suggest a sense of self-reliance. While being by oneself can sometimes be seen as a negative state, these synonyms also highlight the potential benefits of solitude, such as increased productivity, creativity, and self-reflection. Overall, each synonym reflects a slightly different nuance of the concept of being on one's own.