The word of the day is 'quiddity,' pronounced /ˈkwɪd.ɪ.ti/ in the UK and /ˈkwɪd.ə.t̬i/ in the US. This philosophical term captures the inherent nature or essence of a person or thing, addressing the question, 'What is it?' It identifies the specific qualities that distinguish an object from others. Originating from the Scholastic Latin term quidditas, which means 'what,' it was notably used by medieval philosophers like Thomas Aquinas to differentiate between essence and existence. In modern usage, 'quiddity' is often found in academic, philosophical, or literary contexts, where it conveys the soul of a subject. It can also refer to minor eccentricities in personality. For example, one might say, 'The artist struggled to capture the quiddity of the marshland in his painting.' Synonyms include essence, quintessence, and nature, while antonyms include exterior and appearance. The term highlights the unique characteristics that define individuality, making it a valuable addition to both formal and casual discourse.