The term 'by itself' can be expressed in a variety of ways. The five crossword solutions are 'APART' (5 letters), 'SOLITAIRE' (9 letters), 'ALONE' (5 letters), 'perse' (5 letters), and 'separate' (8 letters). 'APART' means to be separated or disconnected from something else, while 'SOLITAIRE' is a card game typically played by one person. 'ALONE' is another word for being without company, and 'perse' is an archaic term meaning to persist or endure. Lastly, 'separate' means to be distinct or APART from something else, and 'ESSENTIALLY' means fundamentally or basically. All of these words describe the concept of being by oneself.