It's very difficult for us to provide scholarly answers to such queries without offending someone, somewhere. The F Word has recently been published and may now be purchased from our book store . I'm curious about its deepest root meaning. Thanks for your site. I always assumed horse chestnut and horseradish were mutations of coarse .
Assumptions can be dangerous in etymology.
There are no early forms of these terms which use the word coarse in place of horse . It is a direct translation of New Latin castanea equina and first appears in its English form in the late 16th century.