noun · An ancient ritual jade tablet, square at the base and rounded or pointed at the top, held by the nobility at ceremonies.

在古代仪式中，公爵朝见天子时通常需要手持青圭。

noun, proper name · An ancient astronomical instrument or sundial used to measure the shadow of the sun to determine time and seasons.

古人通过圭表投下的影子来确定冬至和夏至。

noun · An ancient unit of volume, used figuratively to refer to a very small amount, a smidgen, or a speck.

他做事严谨，哪怕是一圭一铢的误差都要纠正。