Nominal Capital is called the Registered Capital (also known as Authorized Capital) of a company.
This is the maximum amount of share capital that a company is authorized to issue to shareholders as per its Memorandum of Association. It represents the ceiling limit up to which a company can raise capital by issuing shares.
For example, if a company's Memorandum states it can issue 1,00,000 equity shares of ₹10 each, the Nominal/Registered Capital = ₹10,00,000.
The other terms represent different stages of capital:
Issued Capital → Portion of authorized capital actually offered to the public for subscription
Subscribed Capital → Portion of issued capital that investors have agreed to purchase
Reserve Capital → Part of uncalled capital that can only be called upon during winding up of the company
The Nominal Capital is mentioned in the Capital Clause of the Memorandum of Association and must be registered with the Registrar of Companies, hence it is called "Registered Capital."