What is the origin of cordiform?

Cordiform “in the shape of a heart” is a compound of two combining forms: cord- “heart” and -form “shape.” The stem cord- derives from Latin cor, of the same meaning, which is a distant cognate of English heart. As we learned in the etymologies of the recent Words of the Day corvine and pruinose, the Indo-European languages English and Latin share some predictable sound correspondences, and one of the best-known methods of predicting these correspondences is Grimm’s law. Named after the linguist and folklorist Jakob Grimm (of the Brothers Grimm and their fairy tales), Grimm’s law identifies a common pattern: the voiceless stops k (or c), p, and t in Latin and Ancient Greek frequently correspond to the voiceless fricatives h, f, and th in English. In addition to Latin cor and Ancient Greek kardía, which correspond to English heart, we can see this pattern in Latin pater and Ancient Greek patḗr vs. English father. Cordiform was first recorded in English in the 1750s.