The term 'less believable' can be described by three crossword solutions: Lamer (5 letters), Feebler (7 letters), and Phonier (7 letters). Lamer is an informal term used to describe someone or something that is not as good as it should be. Feebler is a synonym for weaker, implying that something is not as strong or powerful as it should be. Phonier is a slang term used to describe something that is not genuine or authentic. All three terms can be used to describe something that is not as believable as it should be.