What's the "een" in Halloween?
early 14c., from Old French controver (Modern French controuver) "to find out, contrive, imagine," from Late Latin contropare "to compare" (via a figure of speech), from Latin com- "with" (see com-) + tropus "song, musical mode," from Greek tropos "figure of speech" (see trope).
Sense evolution (in French) was from "invent with ingenuity" to "invent falsely." Spelled contreve until unexplained 15c. sound change that also affected briar, friar, choir. Related: Contrived; contriving.