on one's (or its) last legs meaning

• [American slang]
  mod. about to expire or become nonfunctional.
  • This car is on its last legs. We have to get a new one.
  • Poor old Chuck is on his last legs.
  
  

• on one's last legs:    On the verge of ut ...
• on someone's or something's last legs last:    [American idiom][f ...
• on so's or sth's last legs:    [American slang]Fi ...