is used with several different meanings in the Bible; such as:
Gloom of the regions of the dead; hell.
( Matthew 22:13)
Empire of Satan. (Colossians 1:13)
Dark; involved in moral darkness or
ignorance; shut off from intellectual light.
( Matthew 6:23)
Shadiness: obscurity
(literally or figuratively);
(Matthew 6:23)
And when the king came in to see the guests,
he saw there a man which had not on a wedding garment: And he saith unto him; Friend, how camest thou in hither not having a wedding garment?
And he was speechless.  Then said the king
to the servants, Bind him hand and foot, and
take him away, and cast him into outer darkenss;
there shall be weeping and gnashing of teeth. 
For many are called, but
few are chosen. 

Matthew 22: 
Giving thanks unto the Father,
which hath made us meet to be partakers of the inheritance of the saints in light:
Who hath delivered us from the power of darkness, and hath translated us into the kingdom
of His dear Son:
In whom we have redemption through His blood,
even the forgiveness of sins...

Colossians 1:    
The light of the body is the eye:
if therefore thine eye be single
thy whole body shall be full of light.
But if thine eye be evil, thy whole body shall be full of darkness.
If therefore the light that is in thee be darkness,
how great is that darkness!
No man can serve two masters:
for either he will hate the one, and love the
other; or else he will hold to the one,
and despise the other.
Ye cannot serve God 
and mammon
Matthew 6: