The Loins,

The 'hip', and by extension,
the procreative powers.
Also, called 'the reins';
"In Scripture, the inward parts;
the heart or seat of the
affections and passions." 
(Noah Webster's 1828)

Stand therefore,
having your loins girt about with truth,
and having on the breastplate of righteousness;
and your feet shod with the preparation
of the gospel of peace...

Ephesians 6:14-15