Other forms: borne in mind; bearing in mind; bears in mind
To bear in mind is to be mindful of or consider something. When you bear in mind the fact that your friend is scared of heights, you won't suggest a ride on a huge Ferris wheel.
Your doctor might give you a clean bill of health, adding, "Bear in mind that you've been sick, and take it easy for a while." When you're babysitting, you might promise the parents that you'll bear in mind the fact that their kids go crazy if they eat sugar. In either case, you're keeping a fact or an idea in your thoughts. This phrase combines the "carry or hold" meaning of bear with an old fashioned sense of mind — "memory."