that act by which any thing is plunged into water or other fluid.

It is used in chemistry for a species of calcination, when any body is immersed in a fluid to be corroded: or it is a species of lotion; as when a substance is plunged into any fluid, in order to deprive it of a bad quality, or communicate to it a good one.

in Astronomy, is when a star or planet is so near the sun with regard to our observations, that we cannot see it; being, as it were, enveloped and hid in the rays of that luminary. It also denotes the beginning of an eclipse of the moon, or that moment when the moon begins to be darkened, and to enter into the shadow of the earth.