Also German (Rare), Dutch (Modern)Pronounced: LAS-seh (Swedish, Norwegian), LA-sə (Danish)Meaning: Scandinavian form of Laurentius (see LAWRENCE or LAURENCE [1]). It is usually a Swedish diminutive of LARS.
Unfortunately many of the comments made are false, are only rumor-based, fictional or just not true. In the case of my name Lasse, the girl-meaning is not true. What the commenters refer to is probably the word "lass", which is both spelled differently and pronounced differently. It is also not true that it is only given as a sort of nickname for Lars in Sweden. This might have been the case many years ago, but now the name is gaining popularity as a boys name here in Denmark, within the last 20 years. I don't know about the current status in other parts of Scandinavia, so if the commenter is only talking about what is going on in Sweden, he might be right, I cannot tell. I only know about Lasse's status here in Denmark where I live and grew up.As a curiosity, I can mention that "Lasse" means sleepy in some French dialects. Something I learned a few years ago, when writing with a Basque girl. In this case though, it is pronounced differently than the name, though. Many people have some difficulty pronouncing the Danish Lasse. That is my overall impression. It is the ending that they apparently miss or find difficult. It is a mix between a Danish "ø" and an "å", if that gets you anywhere? That's it for now. :-)
Lasse is not an Irish word and therefore this name does not mean "girl" in Irish. Lass, a term from Middle English that means "girl" is derived from an Old Norse word that meant "unmarried woman" or possibly a different word that meant "thin." Lasse and lass come from different roots and just happen to look similar.
https://www.beliebte-vornamen.de/3485-lasse.htm
https://www.behindthename.com/name/lasse/top/germany-berlin
https://de.m.wikipedia.org/wiki/Lasse
https://de.m.wikipedia.org/wiki/Lasse_Rempe
https://de.m.wikipedia.org/wiki/Lasse_Kopitz
https://de.m.wikipedia.org/wiki/Lasse_M%C3%BCnstermann
https://de.m.wikipedia.org/wiki/Lasse_Myhr