This is the 942nd most frequent Italian word.
ossia
"Ossia" means "that is to say" or "or rather" in English.
Here, 'ossia' clarifies and specifies the examples of the general term 'pet'.
Vorrei un animale domestico, ossia un gatto o un cane.
I would like a pet, that is, a cat or a dog.
Here, 'ossia' provides a specific detail about what is considered the best solution.
La soluzione migliore, ossia quella più rapida, sarà adottata immediatamente.
The best solution, namely the quickest one, will be implemented immediately.
Here, 'ossia' conveys the meaning or interpretation of solving the problem.