on one's mind(redirected from have something on one's mind (or the brain))
on (one's) mind
In one's thoughts. Jennie's been on my mind lately—do you know how she is? You look worried—what's on your mind?
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
on one's mind
Also, on the brain. In one's thoughts, preoccupying one. For example, The book prize has been on my mind, but I haven't been able to discuss it with you. It is often put as have something on one's mind (or the brain) meaning "be preoccupied with something," as in I didn't mean to be rude; I just have a lot on my mind right now, or John has nothing but girls on the brain. [Mid-1800s]
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.