The Vietnamese word "rư" is an old or literary term that is often used in a poetic context. It can be understood as a variation of the word "ru," which relates to soothing or calming, often associated with lullabies or gentle actions that promote rest.
While "rư" is an interesting word with poetic significance, it is not commonly used in daily speech. It is essential for learners to recognize it primarily in literary contexts and poetry.