Q: I edit writing about crime and justice. I recently scrubbed a piece that used the word “unimagined” instead of “unimaginable” to describe the abuse someone suffered in prison. Is the former term acceptable in this case?
A: The online Merriam-Webster Unabridged Dictionary gives “unimaginable” as one of the definitions of “unimagined,” but three other standard dictionaries that include the two terms define them somewhat differently.
The entries in the online versions of Oxford Dictionaries, Collins, and Macmillan, indicate that “unimagined” refers to something that hasn’t been imagined, while “unimaginable” refers to something that’s hard or impossible to imagine.
Oxford Dictionaries, for example, defines “unimaginable” as “difficult or impossible to imagine or comprehend,” and offers this example: “lives of almost unimaginable deprivation.”
The dictionary defines “unimagined” as “not having been imagined or thought of as possible,” and gives this example: “a previously unimagined degree of economic and social freedom.”
Similarly, the Oxford English Dictionary (a historical dictionary and a different entity from Oxford Dictionaries) defines “unimaginable” as incapable of being imagined, and “unimagined” as not imagined.
The examples for the two words in the OED suggest that they have been used differently since “unimaginable” showed up in the early 1600s and “unimagined” in the mid-1500s.
The earliest citation for “unimaginable” is from A Dictionarie of the French and English Tongues (1611), by Randle Cotgrave: “Inimaginable, vnimaginable, vnconceiuable.”
The OED’s first example for “unimagined” is from The Vnion of the Two Noble and Illustrate Famelies of Lancastre & Yorke (1548), by Edward Hall: “A thyng discended from heauen, of theim vnsought, vnimagined and not deuised.”
Getting back to your question, we think either word would be acceptable to describe the abuse someone suffered in prison, but the meanings would differ.
The term “unimagined” would describe abuse that hadn’t been imagined before, while “unimaginable” would describe abuse that’s difficult or impossible to imagine.
As Angelica sings in the musical Hamilton, “We push away what we can never understand / We push away the unimaginable.”
from Grammarphobia http://www.grammarphobia.com/blog/2016/05/unimagined-unimaginable.html