TITLE: What is the etymology of the term "perverse sheaf"?
QUESTION [46 upvotes]: Grothendieck famously objected to the term "perverse sheaf" in Récoltes et Semailles, writing "What an idea to give such a name to a mathematical thing!  Or to any other thing or living being, except in sternness towards a person—for it is evident that of all the ‘things’ in the universe, we humans are the only ones to whom this term could ever apply.”  (Link here, in an excellent article by Allyn Jackon.)  But a google search for '"perverse sheaf" etymology' gives only nine hits, none of which seem informative.  

What is the etymology of the term "perverse sheaf"?

REPLY [10 votes]: When I was a grad student, a classmate commented about the odd term "perverse" in IH but I defended it. I thought I had figured out the rationale, which I denied had anything to do with perversity in the ordinary sense of that word. My theory was that the "verse" was from "transverse," which is a generic kind of intersection of objects of complementary dimension. By replacing "trans" with "per" we get a more general notion of intersection. The "per" here meant excess or abundance, following the way chemists use that prefix in words like peroxide or permanganate. A perversity in IH in fact specifies how far in excess of the generic expectation the dimension of an intersection with a stratum is allowed to be. My classmate was skeptical, but this theory seemed so plausible to me that I never really doubted it. I am genuinely surprised to be finally refuted.