Something birds, something stones?
Literally: one – morning – one – evening
Alternately: A single day. By extension, a brief and fleeting span of time. Often used in a negative structure to express that something can’t be done in (such) a small amount of time.
Notes: This compound comes to us from the I Ching (易経, in Japanese Ekikyou).
In a variant, the character 朝 is replaced with 旦 (tan), “daybreak.” Meanwhile, while 夕 can often be read as yuu, doing so in either variant of this compound is considered an error.