The term 'not conventional' can be described by four crossword solutions: UNORTHODOX (10 letters), Bizarre (7 letters), NUCLEAR (7 letters), and IMPROPER (8 letters). UNORTHODOX means not following accepted or traditional rules, while Bizarre implies something strange or unusual. NUCLEAR suggests something powerful or extreme, and IMPROPER implies something that is not socially acceptable. All of these words describe something that is not conventional.