This is the 3377th most frequent Japanese word.
根拠
Basis; foundation; grounds; reason.
In this sentence, '根拠' is used to mean 'basis' or 'grounds' for a claim or argument.
彼の主張には十分な根拠がある。
His claim has sufficient basis.
Here, '根拠のない' means 'without basis,' emphasizing the lack of grounds for the rumors.
根拠のない噂を信じないでください。
Please do not believe baseless rumors.
In this context, '根拠' refers to 'evidence' or 'substantiation,' specifically related to scientific reasoning.