This is the 953rd most frequent Vietnamese word.
chu
"Chu" in Vietnamese can mean "uncle" (younger brother of one's father) or a respectful term for an adult male.
Here, 'chú' refers to a paternal uncle who is younger than one's father.
Chú ấy là em trai của bố tôi.
He is my father's younger brother.
Here, 'chú' is used as a polite form of address for an older man.
Con mèo của chú rất đáng yêu.
Your (formal) cat is very cute.
In this sentence, 'chu' is part of the word 'chuột', which means mouse, but 'chu' itself has no distinct meaning.