1 felt strongly and often hidden from other people:
a deep-down certainty
2 in the part of your mind where your strongest and often most secret feelings are:
They know the deep-down, base version of you.
Even though these diseases look so different on the surface, there may be some deep-down, underlying connection between them.
It did not occur to him, the deep-down reason of sordidness that enabled him to compel; but she could think of nothing else.
I must be a sea, full of terrible deep-down currents and smooth on top.
The real question--the deep-down essence of it--is how long the mind, or soul, may retain the enthusiasm and passionate power of creation.
The moment of weakness--of deep-down weariness--passed.
This last thought had far to travel from some unused, deep-down quagmire of the heart, but it came.
