Stupid (adjective)

1. Lacking intelligence or good judgment.
2. Lacking the power of speech or expression.
3. Slow to learn or understand.
4. Mentally dull.
5. Characterized by or showing a lack of thought or good sense.

Origin:

Middle english stupide, from latin stupidus, from stupēre to be stunned.

Examples:

1. She gave a stupid answer to the question.
2. The stupid cat kept knocking over the vase.
3. The stupid film had a predictable ending.
4. The stupid child was always getting into trouble.
5. He made a stupid mistake and regretted it.