WordNet sense 1 (a highly toxic chemical nerve agent that inhibits the activity of cholinesterase):

sarin

WordNet sense 2 (a unit of magnetomotive force equal to 0.7958 ampere-turns):

gi, Gilbert

WordNet sense 3 (a unit of information equal to one billion (1,073,741,824) bytes or 1024 megabytes):

g, gigabyte

WordNet sense 4 (a monarchy in northwestern Europe occupying most of the British Isles; divided into England and Scotland and Wales and Northern Ireland):

Britain, UK, United Kingdom, Great Britain, U.K., United Kingdom of Great Britain and Northern Ireland