frail

An old or weak person might be described as frail.

The word "frail" can sound a bit scary because it's often used to describe someone who's elderly or struggling with health problems. But in everyday language, it's more about describing someone who doesn't have much physical strength or energy left. You might say your grandmother is frail and needs help walking around the house, but she still has her spark and is doing well for her age. The word can also be used to describe something that's delicate or easily broken, like a piece of glassware – it might look beautiful on the shelf, but wouldn't withstand much handling.