Elderlyish 

Already old but you're acting older than your age.

I had no idea your mom was so old

She's not she just being elderlyish

Elderlyish by Socostaind February 18, 2021

elderlying 

Elderlying (v): to carry out the duties or to act in a manner more consistent with those of highly advanced age (coughing randomly without covering your mouth, complaining about random pains to people in an elevator or to tell young people how better they have it).

"Dad can you please stop coughing loudly during the movie"
"Honey, can't you see that dad is elderlying"

elderlying by JewDoc2 November 9, 2019