Synonyms for Problematic (same or very similar meaning)
WordNet sense 1 (open to doubt or debate):
debatable, problematical
WordNet sense 2 (subject to question):
questionable
WordNet sense 3 (making great mental demands; hard to comprehend or solve or believe):
baffling, knotty, tough
WordNet sense 4 (not easy; requiring great physical or mental effort to accomplish or comprehend or endure):
hard
From the ODE community, based on WordNet
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