debatable, problematic, problematical -- (open to doubt or debate; "If you ever get married, which seems to be extremely problematic")
baffling, elusive, knotty, problematic, problematical, tough -- (making great mental demands; hard to comprehend or solve or believe; "a baffling problem"; "I faced the knotty problem of what to have for breakfast"; "a problematic situation at home")
(Sound)
