1. A foundation or ground for belief, argument, or action that lacks factual support or evidence
The accusation was made on an unfounded basis without any concrete proof.
A acusação foi feita em uma base infundada, sem qualquer prova concreta.
2. A premise or reasoning that is not supported by facts, evidence, or logical reasoning
Their concerns were dismissed as being on an unfounded basis.
Suas preocupações foram descartadas por serem em uma base infundada.