Definition of furrow:
(n) :
a line cut in the soil, especially when
plowed in order to plant a
crop; a deep line in the skin of the face, especially on someone's
forehead
"don't walk across that deep furrow in the field."
(v) :
to make a cut in the ground; (About someone's brows or eyebrows) to pull them together due to worry, concentration, etc
"cart wheels can furrow roads."