DC.
This is known as a direct current or D.C.
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction.
AC, Alternating Current.
You can classify electrical current according to different criteria. One important distinction is between DC (direct current - current flows in the same direction all the time), and AC (alternatic current - current changes direction continuously, typically 50 or 60 complete cycles per second).
Direct current= flows in one direction ... AC flows in back and forward ..
That's a "direct" current.
the current which flows in only one specific direction is called as unidirectional current
A DC current flows only in one direction.
With alternating current the current flows alternately one way and then the other.
In one direction - or constant - is called direct current. The other sort is called alternating current.
There are two ways to look at current. Conventional current (measured in amps) flows from positive to negative. This model works for the vast majority of electrical engineering purposes. However, current is created by the movement of electrons. Electrons have a negative charge so electrons moving in one direction will give rise to conventional current in the opposite direction. Therefore, although current flows from positive to negative, electrons flow from negative to positive.
Alternating Current could fit this description in this question.