An alignment of astronomical objects whereby one object comes between the observer (or notional observer) and another object, thus obscuring the latter.
Especially, an alignment whereby a planetary object (for example, the Moon) comes between the Sun and another planetary object (for example, the Earth), resulting in a shadow being cast by the middle planetary object onto the other planetary object.
A seasonal state of plumage in some birds, notably ducks, adopted temporarily after the breeding season and characterised by a dull and scruffy appearance.
Obscurity, decline, downfall
Of astronomical bodies, to cause an eclipse.
To overshadow; to be better or more noticeable than.
(Irish grammar) To undergo eclipsis.