IPA: /sɛpˈtɛntrɪənl/
KK: /sɛpˈtɛntrɪənl/
Relating to the northern part of a region or area.
The septentrional winds brought a chill to the air.
Septentrional is derived from "septentriones" (meaning the seven plowing oxen, referring to the northern constellation of the Great Bear) and the suffix "-al" (meaning pertaining to). The word "septentrional" refers to something that is related to the north or northern regions.
Think of the seven oxen in the northern constellation, which helps you remember that "septentrional" means related to the north.
No commonly confused words.