O40
O40 stands for
- O40, ICD-10 code for polyhydramnios during pregnancy, see list of diseases and conditions in pregnancy, childbirth and the puerperium according to ICD-10 # O30-O48
- O40, FAA code for Elk Grove Airport in Elk Grove, California, United States
- O40, a former trolleybus route in East Berlin, see Trolleybus Berlin (1951–1973)
- O40, an age group of the Senior Badminton World Championship
- O40, an age group of the English Inter-County Badminton Championships
