The term 'CHECKOUT LINES' can be broken down into two crossword solutions: OBIT (4 letters) and UPC (3 letters). OBIT stands for 'OBITUARY, ' which is a notice of death, usually published in a newspaper. UPC stands for 'Universal Product Code, ' which is a type of barcode used to identify products in stores. Together, these two terms refer to the checkout LINES found in retail stores, where customers purchase items using their UPC barcodes and pay for them at the register.