Umbra

The umbra (Latin for shadow) is e darkest part of a shadow. From within the umbra, the source of light is completely blocked by the object causing the shadow. This contrasts with the penumbra where the light source is not completely blocked and there is only a partial shadow.

The umbra is also the comparatively dark central region of a sunspot.

See also eclipse.

The word is in the famous Latin phrase Pulvis et umbra sumus (dust and shadow we are) from Horace (Quintus Horatius Flaccus), Carmina (Book IV, 7, 16)