The term 'PHILOSOPHER's Study' can be broken down into two crossword solutions: ISM (3 letters) and SOUL (4 letters). ISM is an abbreviation for 'IDEOLOGY, ' which is a set of beliefs or principles that guide an individual or group. SOUL stands for 'SPIRITUALITY, ' which is the belief in a higher power or a connection to something greater than oneself. Together, these two terms refer to the study of philosophy, which is the pursuit of wisdom and understanding of the world and its inhabitants.