Thing on a list is a term used to describe an individual element of a list. It can refer to any type of ITEM, such as a word, phrase, number, or object. A thing on a list is typically organized in a specific order and can be used to keep track of information or to make a task easier. In the context of a crossword puzzle, the term 'thing on a list' is usually represented by the four-letter word 'ITEM'.