⟨ZWNJ⟩
The invisible wedge: it keeps two letters from joining where they shouldn't.
The exact opposite of the ZWJ: where two letters would join, the zero width non-joiner keeps them apart. In Persian it is everyday orthography — میخواهم carries a ZWNJ in the middle, with no space at all.
In languages with ligatures, it undoes the wrong ligature at the boundary of a compound word, inserting no width whatsoever. The entity is ‌.
Joined: میخواهم (the Persian letters connect wrongly)
With ZWNJ: می‌خواهم (the join is interrupted in the right place)