Swedish had a word "dygn" that refers to a 24-hour period. It's extremely useful and I am often very annoyed that this word downy exist in English.
English users the word "day" most of the time and just home there won't be any miscommunication, or they use cumbersome versions like "24 hours".
It also leads to very silly expressions like "I'll be on vacation there for 3 days 2 nights", instead of just being able to say "I'll be there for 2 dygn".