septentrional
northern
septet
a group of seven
+
-ional
adjective suffix
Septentrional means northern and can be remembered by thinking of a septet0 (group of seven0) of stars in the northern sky (the Big Dipper), with -ional1 being an adjective suffix1.
adjective
- northernRelating to or situated in the northLos países septentrionales de Europa tienen inviernos largos. // The northern countries of Europe have long winters.