What do the following name and words have in common?

DOOR
DORM
DRAM
ODIN

Answer:

Each word is made up of two common, two-letter abbreviations mushed together:

DOOR - Doctor of Osteopathy and Operating Room
DORM - Doctor of Osteopathy and Room
DRAM - Doctor and A.M. 
ODIN - Doctor of Optometry and Inches