Alkalis and bases differentiation

[Udhaya]

Hi, I have a doubt on the topic of bases and alkalis. I have learned that a alkali is a soluble base so does that mean Sodium Oxide(Solid) is a alkali and Lithium Hydroxide(Solid) is a alkali. Or are they considered alkali when they are dissolved? For example, Sodium Oxide becomes sodium hydroxide which is alkali in aqueous form.

 

[StanEvans]

I believe that they would still be considered as alkali when dissolved as it would result in a solution that had a pH higher than 7, it would be that OH- ions that would cause the alkaline pH which are from that hydroxide in this case.