Which country has the world's only non-quadrilateral national flag? Nepal. Its flag is made from two joined pennants, creating a distinctive double-pennon shape rather than a rectangle or quadrilateral.
The modern design was adopted on December 16, 1962, after Nepal’s constitutional change standardized the flag. Its crimson-red field represents bravery and is associated with Nepal’s national flower, the rhododendron. A deep-blue border symbolizes peace and harmony. The upper pennant bears a stylized moon, while the lower one carries a sun.
Nepal’s flag is often called triangular, but that is only partly accurate: it is a concave, two-part pennant with five outer points. The moon and sun also distinguish it from ordinary triangular flags used by clubs, organizations, or maritime signal systems. A common mix-up is Bhutan, whose flag is unusual because it features a dragon, but it remains a conventional quadrilateral flag.