Definitions of debt securities and private placement clarify scope and issuance conditions under SEBI debt securities regulations. Definitions establish regulatory scope: debt securities as non-convertible instruments including debentures, bonds and securities of corporates and REITs/InvITs, excluding government bonds, security receipts and securitized instruments. Issuer covers companies, PSUs, statutory corporations and registered REITs/InvITs. Key terms defined include designated stock exchange, book building, offer document (prospectus or shelf prospectus) and private placement as an offer to a select group under Companies Act conditions. Net worth and wilful defaulter adopt statutory and RBI-related meanings.