perpendicular plate

noun

per·​pen·​dic·​u·​lar plate ˌpər-pən-ˈdik-yə-lər- 

1

: a flattened bony lamina of the ethmoid bone that is the largest bony part assisting in forming the nasal septum

2

: a long thin vertical bony plate forming part of the palatine bone compare horizontal plate