1. A theory or explanation that differs from the mainstream or conventional viewpoint on a subject
The scientist proposed an alternative theory to explain the phenomenon.
O cientista propôs uma teoria alternativa para explicar o fenômeno.
2. In logic and law, a secondary theory or claim presented as an option if the primary one fails
The defense presented an alternative theory of the crime.
A defesa apresentou uma teoria alternativa sobre o crime.
3. An unconventional or non-mainstream explanation, sometimes lacking scientific consensus
Some people believe in alternative theories about historical events.
Algumas pessoas acreditam em teorias alternativas sobre eventos históricos.