"Young Girl, Maiden(Celtic) People's victory(Greek - Male) "
The name Lasse is commonly a unisex name from the "Greek" origin that means "Young Girl, Maiden(Celtic) People's victory(Greek - Male) ".
Male meaning: One crowned with laurel, Victorious one. The Norse form of Laurence.
Female meaning: Young Girl, Maiden(Celtic) People's victory(Greek - Male)

The pronunciation of Lasse is (LA say).