During a take-off roll out down the runway, in a tail-dragger airplane, what is the period of time called where the plane is level, with the main gear still on the runway, but the tail has come up off the ground and before you pull back on the stick to begin climb-out?
There is no term (that I am aware of) referring to only the portion of the takeoff while the tail is off the ground.
In general, the attitude where just the two main wheels are touching the ground is called "two-point." Likewise, with the tail wheel also on the ground, it is called "three-point."
Specifically, a two-point landing is sometimes called a "wheel landing".