I researched, it seems like several sources list the English word "casual" or "informal." Examples might be "casual clothing" which might be no tie and jacket, or even jeans. Casual can also describe a social event, such as a bunch of friends going to a movie rather than dressing up and going to the theater. These uses are important to let you know what to expect before you go somewhere socially. You can also use this word in English as a kind of "relaxed" with few expectations, such as "casual dating" or "a casual interview." "Informal interview" might also be used, but in relationships "casual" is the better word, it's just the one that's used. Again, it's just setting expectations of what to wear and what social situations might arise. How does this fit with the Chinese meaning?

yes ,i see

er…nina, I think you wanted to say “get it” or "I see". hehe~~~

i konw

thank you all the kind