An Occultation occurs when one celestial body hides another, i.e., it enters an observer's line of site and is large enough that the further body is not visible.
In contrast, a Transit is one body hiding part of another by passing in front of it, and an eclipse is one body throwing a shadow on another, e.g., two planets specifically in line with their star.
Arecibo Occultation Survey (AO)
Exoplanet Eclipse Light Curve
Stellar Radius Determination