1. A competing or alternative theory that challenges or contradicts another established theory, particularly in academic, scientific, or intellectual discourse
The Big Bang theory had to overcome several rival theories before gaining acceptance in the scientific community.
A teoria do Big Bang teve que superar várias teorias rivais antes de ganhar aceitação na comunidade científica.
2. In philosophy and epistemology, a theory that presents an alternative explanation or interpretation of the same phenomena
The competing interpretations of quantum mechanics represent rival theories about the nature of reality.
As interpretações concorrentes da mecânica quântica representam teorias rivais sobre a natureza da realidade.