unnerve

To cause to lose courage or firmness of purpose.

To deprive of nerve, force, or strength; weaken; enfeeble; hence, to deprive of power or authority, as a government.

To deprive of nerve, force, or strength; to weaken; to enfeeble.

To deprive of nerve, force, or strength; to weaken; to enfeeble.

To upset.

disturb the composure of