The Vietnamese word "lưu cầu" has a rich history and can be understood in a couple of ways.
Literal Meaning: Traditionally, "lưu cầu" refers to a "jade-inlaid sword." This term combines "lưu" (which can mean to preserve or keep) and "cầu" (which can refer to a sword or a weapon). The jade-inlaid sword symbolizes something precious and beautiful but is also a weapon, representing conflict or struggle.
Figurative Meaning: In a more poetic sense, it highlights the idea of conflict not being resolved through physical means (like a sword) but through emotional struggles (like cares and melancholy). This usage can be found in literature, such as in the quote: "giết nhau chẳng cái lưu cầu, giết nhau bằng cái ưu sầu độc chưa" (not to kill one another with jade inlaid swords, but with cares and melancholy, oh how wicked!).