Inadequate (adjective)

1. Not good enough; insufficient.
2. Not having enough of the required qualities or resources.

Origin:

Mid 17th century: from in- "not" + adequate, on the pattern of latin inadequatus.

Examples:

1. The response was inadequate.
2. The explanation was inadequate.
3. The preparation was inadequate.
4. The support was inadequate.
5. The equipment was inadequate.