doddery
We now have Moira's mother, who was living alone in an Edinburgh flat and becoming increasingly tottery, living with us.
Thereafter, Churchill slid inexorably downhill, getting feebler, deafer, more tottery.
If your tottery ancient parent wants to go to Paris, which you feel that they will not survive, they should still (to my mind) be supported in their wishes.
McKellen's Lear is so tottery, closer and closer to capsizing in every scene.

SMART Vocabulary: related words and phrases

Weakness and vulnerability
Achilles heel
asthenia
at a low ebbidiom
atonic
atony
fragile
fragility
frail
glass jaw
helpless
shakily
shakiness
shaky
sitting duck
sitting target
weakling
weakly
weakness
weedy
wetly