←
Proto-Mon-Khmer *p(ɗ)am (inherited)
←
Proto-Mon-Khmer *cn₁am (inherited)
←
Proto-Vietic *ɗam (inherited)
←
Proto-Vietic *c-nəm (inherited)
←
Vietnamese niên (mention)
→
Vietnamese lăm (mention)
→
Vietnamese bộ năm (compound)
→
Vietnamese rằm (mention)