「GMT(Greenwich Mean Time)」とは、国際的な基準時刻のひとつです。イギリスのグリニッジ天文台を通る子午線(南北線)を基準とした「平均太陽時」を指し、「グリニッジ標準時」や「グリニッジ平均時」と訳すものです。


GMT (Greenwich Mean Time) is an international standard time. It refers to "mean solar time" based on the meridian (north-south line) that passes through Greenwich Observatory in the United Kingdom, and translates to "Greenwich Mean Time" or "Greenwich Mean Time.

The GMT function in a watch refers to the ability to simultaneously display two time zones: local time (local time) and home time (GMT).