Final answer:
The principle of indefeasibility in the Torrens system means that a purchaser is protected from unregistered interests or claims against the property. They do not need to investigate the title or give prior notice to the registrar. The purchaser is deemed to have knowledge of all registered interests.
Step-by-step explanation:
The principle of indefeasibility under the Torrens system means that a purchaser of a property is protected from any unregistered interests or claims that may exist against the property. Under this principle, a purchaser does not need to investigate the title or give prior notice to the registrar when applying for registration. Additionally, the principle of indefeasibility ensures that a purchaser is deemed to have knowledge of all registered interests, even if they are unregistered.