Step 1: Define Dissolution.
Dissolution signifies the total termination of a partnership firm, involving the cessation of business operations and the settlement of all financial matters.
Step 2: Relevant Legal Sections.
- Section 32 covers partner retirement.
- Section 35 addresses partner insolvency.
- Section 37 outlines the rights of an outgoing partner in specific circumstances.
- Section 39 provides the definition of firm dissolution, marking the end of the partnership agreement among all partners.
Step 3: Summary.
Consequently, the dissolution of a partnership firm is defined under Section 39 of the Partnership Act, 1932.
Final Answer: [\boxed{\text{Section 39}}]