The term 'luckless one' can be described by two crossword solutions: SAP and LOSER. SAP is an acronym for System Application and Products, which is a suite of software applications used to manage business operations and customer relations. LOSER is a slang term for someone who has been unsuccessful or has suffered a defeat. Therefore, the term 'luckless one' can be used to describe someone who has been unsuccessful in their endeavors due to a lack of luck.