- debatable, problematic, problematical - open to doubt or debate; "If you ever get married, which seems to be extremely problematic"
Antonym: unquestionable (indirect, via questionable)
- baffling, knotty, problematic, problematical - making great mental demands; hard to comprehend or solve; "a baffling problem"; "I faced the knotty problem of what to have for breakfast"; "a problematic situation at home"
Antonym: easy (indirect, via difficult)