Well-founded (adjective)

1. Having a solid basis or foundation, grounded in good reasons and evidence.
2. Having a rational or scientific explanation, backed up by evidence.

Origin:

Formed by combining 'well' and 'founded'.

Examples:

1. The argument that climate change is a hoax is not well-founded.
2. Her belief in the paranormal was not well-founded and lacked scientific evidence.
3. The concern about the safety of the new drug was well-founded, given the results of recent clinical trials.
4. His prediction of the stock market crash was based on well-founded economic data.
5. Her accusations of fraud were well-founded and led to a criminal investigation.