What is scientific meaning for emerge?

To move out / come out or away from something

When we're talking about something that's emerging, we're talking about a characteristic of a certain object we're observing which couldn't be directly inferred from its known constitutional parts.

If we know water is made out of oxygen and two hydrogen molecules, we cannot predict certain qualities it has. What we need to know and what is important is that we also know the interaction between the constitutional parts of our object so that we can properly explain the new observed characteristic.