约会
yuē huì
appointment
engagement; date; CL:次[ci4],個|个[ge4]; to arrange to meet
bind (约) + people gathering to speak (会) = a date or appointment
约 carries the idea of tying things down — committing someone to a time and place. 会 pictures people coming together with words, which is exactly what arranging a meeting involves.
他们今晚有一个约会，打算一起吃晚饭。
tā men jīn wǎn yǒu yī gè yuē huì，dǎ suàn yī qǐ chī wǎn fàn。
they have a date tonight and plan to eat dinner together.
她和朋友的约会取消了，所以她待在家里。
tā hé péng yǒu de yuē huì qǔ xiāo le，suǒ yǐ tā dāi zài jiā lǐ。
her appointment with a friend was cancelled, so she stayed home.