Antonyms of adj adequate

3 senses of adequate

Sense 1
adequate (vs. inadequate), equal -- (having the requisite qualities or resources to meet a task; "she had adequate training"; "her training was adequate"; "she was adequate to the job"; "he was equal to the task")

inadequate (vs. adequate), unequal -- (lacking the requisite qualities or resources to meet a task; "inadequate training"; "the staff was inadequate"; "she was unequal to the task")
        => deficient, lacking (predicate), wanting (predicate) -- (inadequate in amount or degree; "a deficient education"; "deficient in common sense"; "lacking in stamina"; "tested and found wanting")
        => incapable, incompetent, unequal to (predicate) -- (not meeting requirements; "unequal to the demands put upon him")
        => short-handed, short-staffed, undermanned, understaffed -- (inadequate in number of workers or assistants etc.; "they're rather short-handed at the moment"; "overcrowded and understaffed hospitals")

Sense 2
adequate, decent, enough -- (sufficient for the purpose; "an adequate income"; "the food was adequate"; "a decent wage"; "enough food"; "food enough")

INDIRECT (VIA sufficient) -> insufficient, deficient -- (of a quantity not able to fulfill a need or requirement; "insufficient funds")

Sense 3
adequate, passable, fair to middling, tolerable -- (about average; acceptable; "more than adequate as a secretary")

INDIRECT (VIA satisfactory) -> unsatisfactory -- (not giving satisfaction; "shops should take back unsatisfactory goods"; "her performance proved to be unsatisfactory"; "life is becoming increasingly unsatifactory"; "our discussion was very unsatisfactory")

Similarity of adj adequate

3 senses of adequate

Sense 1
adequate (vs. inadequate), equal -- (having the requisite qualities or resources to meet a task; "she had adequate training"; "her training was adequate"; "she was adequate to the job"; "he was equal to the task")
       => adequate to (predicate), capable, equal to (predicate), up to (predicate) -- (having the requisite qualities for; "equal to the task"; "the work isn't up to the standard I require")
       => competent -- (adequate for the purpose; "a competent performance")
          Also See-> satisfactory#1

Sense 2
adequate, decent, enough -- (sufficient for the purpose; "an adequate income"; "the food was adequate"; "a decent wage"; "enough food"; "food enough")
       => sufficient (vs. insufficient) -- (of a quantity that can fulfill a need or requirement but without being abundant; "sufficient food")

Sense 3
adequate, passable, fair to middling, tolerable -- (about average; acceptable; "more than adequate as a secretary")
       => satisfactory (vs. unsatisfactory) -- (giving satisfaction; "satisfactory living conditions"; "his grades were satisfactory")