right-hand man

One's primary or most trusted assistant. Not necessarily a man. I can always rely on Jake to help me—he's been my right-hand man for years now.

Also, right-hand woman. A trusted helper, as in Give it to Jill, she's my right-hand man. Based on the idea that in most people the right hand is the stronger of the two, this idiom today usually disregards gender, as in the example. However, in the the 17th and 18th centuries it also meant a soldier in a post of command on the right side of a cavalry unit, and then always denoted a man. [c. 1800]

COMMON Someone's right-hand man or right-hand woman is their close assistant and the person they trust to help and support them in everything they do. He was always by her side and supported her in everything she did. He was her right-hand man and he travelled with her everywhere. You'd be Oliver's right-hand woman. He needs somebody he can really rely on, don't you, Oliver? Note: Less often, people talk about someone's right-hand person. Ricard was her husband's right-hand person and took an active part in the broadcasting business and all other ventures he was involved in. Note: This expression is commonly used to talk about politics or business. Note: There are several possible explanations for this expression. One is that the right side of the body is traditionally associated with skill and strength. Another is that it may refer to the soldier who was responsible for the right side of a troop of horses. Also, in the past, the position on the right of the leader at political or social gatherings was the place of honour.