Hi! I believe we call it "transit" of the planet (from the Earth, we can see the transit of Mercury and Venus only, of course!) :) Take a look on this beautiful movie of the 2012 Venus transit recorded by the Solar Dynamics Observatory (SDO): https://www.youtube.com/watch?v=4Z9rM8ChTjY

If the planet were just the right size and just the right distance away to completely block the bright part of the Sun (the photosphere), it could still be called a solar eclipse. But probably the most general term is transit, since the Moon *is* transiting the Sun as well as completely eclipsing it during a total solar eclipse.

Did you know that astrophysicists use just those types of transits to help them understand the characteristics of stars outside our solar system? Here's a short video that tells you how it works: https://youtu.be/6AsPeabSu24