Historic means (1) momentous or (2) historically significant. Historical means (1) of or relating to history, or (2) of or relating to the past. The words were originally synonyms—which historic developing as a shortened historical—but they began to diverge in meaning around the 18th century, and the difference has solidified over time.
Buildings, villages, districts, and landmarks deemed historically important are often described as historic because they are historically significant in addition to being of or related to history. Societies dedicated to recognizing and preserving these things are called historical societies because they are concerned with history but not momentous in themselves.
Related
Historic and historical belong to that troublesomely inconsistent class of -ic and -ical word pairs. For other pairs, see ironic–ironical, economic–economical, and metaphoric–metaphorical.
Examples
In these examples, historic is correctly used as a synonym of momentous or notable:
Early morning parties were held across the city to mark the historic event. [CTV.ca]
That’s in addition to historic droughts and fires in Texas, record low temperatures in Seattle, and snow and flooding in the Midwest. [NPR]
And these writers correctly use historical for things that relate to or are concerned with history or the past:
Historical fiction is currently enjoying a tremendous renaissance, both in terms of literary and commercial recognition. [Guardian]
Optimism that stock prices will rise over the next six months remained below its historical average of 39% for the second consecutive week. [Forbes]
When we cut to the USS Arizona “a few minutes after eight”, the historical footage creates a narrative that is genuinely chilling. [Sydney Morning Herald]
