Definition of right-hand man noun from the Oxford Advanced Learner's Dictionary

 

right-hand man

 noun
noun
BrE
 
; NAmE
 
[singular]
 
jump to other results
a person who helps somebody a lot and who they rely on, especially in an important job the President’s right-hand man The former newspaper editor became David Cameron's right-hand man in Downing Street. He agreed to the deal after consulting his lawyer and right-hand man, Charles Alton.
See the Oxford Advanced American Dictionary entry: right-hand man