| a. | 1. | (Anat. & Zool.) Situated in front of the frontal bone, or the frontal region of the skull; ectethmoid, as a certain bone in the nasal capsule of many animals, and certain scales of reptiles and fishes. |
| Adj. | 1. | prefrontal - anterior to a frontal structure; "a prefrontal bone"; "prefrontal lobes" |