Origin: Latin suffix -ate
Inadequate has 4 different meanings across 1 category:
An individual who is inadequate.
"The manager found the new employee inadequate for the role due to his lack of technical skills."
In plain English: There is no noun form of inadequate; it is only an adjective used to describe something that isn't good enough or sufficient for its purpose.
"There was an inadequacy in his plan that would cause delays during the construction phase."
lacking the requisite qualities or resources to meet a task
"inadequate training"
"the staff was inadequate"
"she was unequal to the task"
of insufficient quantity to meet a need
"an inadequate income"
"a poor salary"
"money is short"
"on short rations"
"food is in short supply"
"short on experience"
"the jejune diets of the very poor"
Not adequate; not fit for the purpose
"The shelter was inadequate to protect the family from the severe storm."
In plain English: Inadequate means not good enough to do what is needed.
"The shelter was far too small and inadequate to keep them warm during the winter storm."
The word inadequate comes from combining the prefix in- with adequate to mean not sufficient or fitting its purpose. It entered English as a straightforward negation of an existing term rather than through a complex historical shift.