Synonyms for Unsuitable (same or very similar meaning)
WordNet sense 1 (not capable of being applied):
inapplicable
WordNet sense 2 (having no bearing on or connection with the subject at issue):
irrelevant
WordNet sense 3 (having undesirable or negative qualities):
bad
WordNet sense 4 (not worthy of being chosen (especially as a spouse)):
undesirable
WordNet sense 5 (not appropriate for a purpose or occasion):
improper, wrong
WordNet sense 6 (not suitable for a particular occasion etc):
inappropriate
From the ODE community, based on WordNet
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