The Vietnamese word "lão suy" is an adjective that means "senile" or "decrepit." It is used to describe someone, usually an elderly person, who is experiencing a decline in mental or physical abilities due to old age.
"Lão suy" specifically refers to the decline due to age. However, if discussing general deterioration not necessarily related to age, you might use "suy yếu," which means "weakened" or "deteriorated."