heorte, f.n: the heart.
Also, the topic of my paper today in session 500 at the 50th International Congress on Medieval Studies!
This lovely artefact is from the Staffordshire Hoard (photo from swns.com). This was as close as I could get to an Anglo-Saxon image of a heart. Yes, I know, it’s probably not meant to be a heart at all.
Although these eagle-like birds do form the shape of a heart in the space between their heads, this is probably just a coincidence. The heart symbol originates in the later Middle Ages, with early examples or direct predecessors in the 13th to 14th centuries. One of the earliest examples is this one, the Empress Zoe mosaic in the Hagia Sophia in Istanbul. It probably dates from 1239. You can see little hearts on the Bible held by Christ.
Photo of mosaic by Myrabella.