Global Depository Receipts (GDRs) are negotiable certificates that allow an issuer to raise capital simultaneously in two or more markets through a global offering, where each GDR typically represents a fixed number of underlying company shares (e.g., 1 GDR = 10 shares).
Source: Foreign Capital Issuance, chapter 3
For a 1-mark question, just define GDR in one clear sentence. Key terms examiners look for: negotiable certificate, raise capital in two or more markets, and optionally the fixed ratio of GDR to underlying shares. Avoid writing more than 2 lines.