1. Check each statement one by one

Option A

Statement: A circular path around the nucleus in which an electron moves is proposed as Bohr's orbit.

In Bohr’s atomic model, electrons move in certain permitted circular orbits around the nucleus. These are called Bohr orbits.

So, Option A is correct.

Option B

Statement: An orbital is the one electron wave function $(\psi)$ in an atom.

In quantum mechanics, an atomic orbital is described by a one-electron wave function $\psi$.

So, Option B is correct.

Option C

Statement: The existence of Bohr's orbits is supported by hydrogen spectrum.

Bohr explained the line spectrum of hydrogen by assuming electrons can exist only in certain quantized orbits. Thus, hydrogen spectrum provided strong support for Bohr’s model.

So, Option C is correct.

Option D

Statement: Atomic orbital is characterised by the quantum numbers $n$ and $l$ only.

An atomic orbital is characterized by three quantum numbers:

• principal quantum number $n$
• azimuthal quantum number $l$
• magnetic quantum number $m_l$

The electron in that orbital is further described by spin quantum number $m_s$.

Therefore, saying that an atomic orbital is characterized by $n$ and $l$ only is incorrect.

So, Option D is incorrect.

2. Conclusion

The incorrect statement is:

$\boxed{D}$