noun

• (anatomy) Initialism of gallbladder.
• (informal, pharmacology) Initialism of goofball (“barbiturate”). [(informal, often derogatory, sometimes endearing) A foolish or silly person or animal.]
• (crystallography) Initialism of grain boundary. [An internal interface that separates neighbouring misoriented single crystals in a polycrystalline solid.]
• Initialism of Great Britain. [The island (and sometimes including some of the surrounding smaller islands) off the north-west coast of Europe made up of England, Scotland, and Wales.]
• Initialism of Gilgit-Baltistan. [An administrative territory of Pakistan, part of Pakistani-Administered Kashmir, as well as the wider Kashmir, region. Capital: Skardu.]
• Abbreviation of Green Bay in Wisconsin, USA.
• Initialism of Game Boy.
• (chemistry, military) Initialism of German agent B (US designation for the nerve gas sarin).
• Initialism of Guantanamo Bay. [A bay in Southeast Cuba.]
• (linguistics) Initialism of Government and Binding.