A total eclipse is one in which the celestial body is
completely
obscured by the shadow or body of another. The key word is completely.
A total
solar eclipse has the
moon completely blocking the
sun with
respect to some point on earth. A total
lunar eclipse has the moon
completely inside the
umbra of the earth's shadow.
With solar eclipses, a distinction should be drawn between the
annular eclipse and the total eclipse. In an annular eclipse, there
is a thin ring round the disk of the moon that is not covered. This
is because the moon does not have a perfectly circular orbit around
the earth, nor does the earth have a perfectly circular orbit around
the sun. When there is an eclipse and the moon is further away it takes
up a smaller arc of the sky. Likewise, when the earth is closer to the
sun, the sun will take up a larger arc of the sky. If the sun's arc
is larger than the moon's arc, it will be an annular eclipse.