Fat or swollen foot where one's finger may press and leave semi-permanent indent! (medical name = Pitting Oedema).
Generally caused by running in flip flops with heavy shopping bags and causing internal foot injury that cannot be healed. Nanna foot likes to swell in the heat and when heels are too high. Also doesn't like alcohol and adds to a nasty hangover.
When Nanna Foot gets nasty, the swelling can reach the lower leg and appear much like its sister, Elephantitis minor.