1
general::
Exactly what was needed. For example, This steak is just what the doctor ordered, or You've been a great help in our office? just what the doctor ordered. This expression alludes to a physician's prescription for a cure. [First half of 1900s]
American Heritage Idioms
2
general::
Phrase(s): just what the doctor ordered
Fig. exactly what is required, especially for health or comfort. • That meal was delicious, Bob. Just what the doctor ordered. • Bob: Would you like something to drink? Mary: Yes, a cold glass of water would be just what the doctor ordered.
McGrawhill's American Idioms And Phrasal Verbs