Synonyms for Inadequate (same or very similar meaning)
WordNet sense 1 (not sufficient to meet a need):
poor, short
WordNet sense 2 (of a quantity not able to fulfill a need or requirement):
deficient, insufficient
WordNet sense 3 (not meeting requirements):
incapable, incompetent
WordNet sense 4 (inadequate in amount or degree):
lacking
From the ODE community, based on WordNet
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