inadequate
adj.adj. not good enough or not enough in amount for what you need. You use this when something is lacking the quality or quantity required to do a job properly.
adj. lacking the quality or quantity required for a particular purpose; insufficient. Often used to describe resources, preparation, or a person's sense of self-worth in a specific context.
The old heating system is inadequate for this large house.
The committee found that the safety measures were inadequate to prevent a similar accident in the future.
Despite his extensive experience, he often felt inadequate when surrounded by colleagues who had spent decades researching such a niche area of theoretical physics.
From in- + adequate.
Commonly followed by the preposition 'for' or an infinitive 'to' clause.
The food was inadequate of our needsThe food was inadequate for our needsInadequate takes the preposition 'for' when referring to a requirement, not 'of'.