Two Hebrew words that almost every Jewish person knows are sourced in the same root word.
"Siddur" is the prayer book used around the year, and "Seder" is the opening event of Passover which is part ritual service and part extended dinner feast.
Both are derived from the word "Order." Prayers are organized to provide inspiration and order to the day, and the Seder night has a 15-step process which we rigorously follow.
Oddly enough, the textbook we follow during the Seder isn't called Siddur, but "Haggadah" which is based on G-d's instruction (Exodus 13:8) "Ve-higadeta Le-vincha" ("and you shall teach your child.")
So why call the book Haggadah and not Siddur which would better reflect the nature of the Passover Seder?
One answer is that we are often so consumed by order and daily routines that we forget why we are even doing it all.
Passover night reminds us of the reason we are doing it all: To tell the story and pass it on to the next generation.