SpellCheck agrees with me. But what do we know?
A piece of broken pottery or glass; a fragment.
But now I see it spelled sherd. S-h-e-r-d.
SpellCheck underlines it in red, and to me it has the not-quite-right look of a word with an errant letter.
My style books are no help. The APA (American Psychological Association) style guide, which I use to write most of my education papers, doesn't list the word. MLA (Modern Language Association), in which I write my literary papers), doesn't seem to address the word. The formidable Chicago Style Manual, which I use to write history papers and travel guides, doesn't list it.
Even my AP (Associated Press) Style Book, which I use for newspaper writing and which has explanatory listings for when to use shake up (v.) or shakeup (n., adj.) and calls for a hyphen in mo-ped, contrary to Webster's New World College dictionary, is silent on the spelling of shard/sherd.
Google to the rescue in the form of the National Geographic Style Manual! The listing says to use sherd when writing in the archaeological sense of potsherds or sherds of pottery; use shard for all other senses.
So ... if I break a flower pot I bought at Wal-Mart yesterday, I pick up the shards. If I find a broken flower pot in what a century ago was a dump site, I excavate the sherds.