Can you teleport within an area warded by Forbiddance? It's already been established you can teleport out of it, but not whether, once inside, you can teleport from one part of it to another.
You create a ward against magical travel that protects up to 40,000
square feet of floor space to a height of 30 feet above the floor. For
the duration, creatures can't teleport into the area or use portals,
such as those created by the gate spell, to enter the area. The spell
proofs the area against planar travel, and therefore prevents
creatures from accessing the area by way of the Astral Plane, Ethereal
Plane, Feywild, Shadowfell, or the plane shift spell.
The phrasing uses both phrases, "into" and "enter". If you teleport from one area to another, you are going into an area, and if you enter an area that would only block teleportation from outside.
As such, I'm not sure whether the spell could be used, say, to ward a battleground so that the enemy couldn't teleport around within said area easily, or used within a mage's private area to prevent an enemy teleporting around smashing things.
So, can I teleport within an area warded by Forbiddance?
Best Answer
You can teleport from one place within the warded area to another within the warded area
Since, as you point out, the text of the spell only says you can't teleport from outside to inside, nothing stops you RAW from teleporting from one place within the warded area to another place within the warded area.
Just quoting again from forbiddance (PHB, pg. 243):
I'd also say that teleporting whilst already within the area would also be RAI (Rules as Intended) since the intention of the spell seems to be to keep people out of the area, not to annoy those already within the area.