Charitable purpose: commercial activities allowed only if incidental to objects and receipts stay within statutory quantitative limit. Section 2(15) confines charitable purpose by excluding activities in the nature of trade, commerce or business or services for consideration unless such activity is undertaken in the course of actual carrying on of the GPU object and the aggregate receipts from such activities in the previous year remain within the statutory quantitative limit; interpretation focuses on the manner of carrying on the activity, incidental nature of income, and harmonisation with provisions requiring separate accounts and authority scrutiny.