by Thatonedramaticperson March 7, 2021

Any previous day within the last four to five days, usually said by small children who don't yet have a clear concept of time. Originally coined in early 2019 by a three-year-old girl.
by evilsammy March 2, 2020

by Jahxujsbdbcue October 9, 2021

My 3 year old doesn't differentiate yesterday, last night, the other day and a couple days ago well so we accept "lasterday" to cover all bases. "Do you remember "lasterday" you let me eat a lot of ice cream?
by Sure Guy April 18, 2019

by mrsnoms December 26, 2019

I quit smoking lasterday.
by Wimperdinkle December 25, 2016

For those that work overnight, it was during the shift that started last night which could have possibly been early morning.
by randonme March 16, 2019
