What does borealis mean?
Borealis is a Latin-derived adjective meaning 'of the north' or 'northern'. In modern English its use is overwhelmingly confined to one celebrated phrase: aurora borealis, the scientific and poetic name for the northern lights, the luminous displays caused by charged solar particles striking gases high in Earth's polar atmosphere. Because the word survives almost solely inside this fixed expression, encountering it anywhere else feels distinctly literary or scholarly. Its counterpart, australis ('southern'), names the corresponding phenomenon of the far south. For most readers the word carries connotations of cold beauty, darkness, and natural wonder, evoking Arctic night skies rather than any ordinary geographic description. Knowing borealis is useful not for everyday conversation but for appreciating scientific writing, travel literature, and the classical roots that still shape English vocabulary about direction and place.
adjectiveOf the north or northern; relating to the north. The word is used almost exclusively in the fixed phrase 'aurora borealis', denoting the northern lights, and is rarely employed as a general standalone adjective.
- (in the fixed phrase aurora borealis) northern; relating to or occurring in the far north — the standard and virtually sole current use, naming the northern lights.
- Of or belonging to the north wind or the north (rare, chiefly in scientific or literary contexts echoing classical Latin usage).
"We travelled to Tromsø to witness the aurora borealis dancing across the winter sky."
"The forecast promised clear skies, ideal conditions for viewing the aurora borealis."
"In classical Latin poetry, the borealis wind swept down from the mountains of the north."
Every time you admire the northern lights, you're using a Latin word for 'northern' coined by Galileo himself — he thought the glowing skies were sunlight reflecting off the atmosphere at dawn.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of borealis
Borealis comes from Latin boreālis, meaning 'northern', formed from Boreas, the Greek god and personification of the north wind. English adopted the word in the early modern period, most famously in the phrase aurora borealis, which Galileo used in the early 17th century for the dawn-like glows he observed. It shares this Greco-Latin lineage with other directional terms such as australis (from Auster, the south wind), and with words like hyperborean, literally 'beyond the north wind', describing the legendary far-northern realm of Greek myth.
How borealis is actually used
Almost always encountered within the phrase 'aurora borealis'; using it as an independent adjective sounds learned or archaic. Capitalization varies: 'aurora borealis' is often lowercase in running text, while some style guides capitalize it as a proper name. In everyday speech many people simply say 'northern lights'.
Easily confused with borealis
Australis means southern and appears in 'aurora australis', the southern lights, whereas borealis means northern.