senescence -- Ann and Auntie Mary

se·nes·cent  (s-nsnt) adj. Growing old; aging. [Latin senscns, senscent-, present participle of senscere, to grow old, inchoative of senre, to be old, from senex, sen-, old; see sen- in Indo-European roots.] se·nescence n.

The American Heritage® Dictionary of the English Language.

Ann and I love our senescent neighbor Annabella: Annabella and I go to exercise classes together, and Ann helps Annabella clean up her house.