1 general:: Annoying or bothering someone. For example, She was constantly in my hair, overseeing everything I did, or Dad was working on taxes, and the children were getting in his hair. This expression alludes to entangling one's hair. [Mid-1800s] The antonym, out of someone's hair, is often used as an imperative, as in Get out of my hair! [c. 1900]
American Heritage Idioms