A neologism coined by Parmandil and Luinyelle, posted on 2024-05-07 in the Vinyë Lambengolmor Discord Server (VLDS), a combination of ondo “stone” and sercë “blood”.
Sindarin
seregon
noun. stonecrop, plant with red flowers, (lit.) blood of stone
A plant with red flowers growing on top of Amon Rûdh (S/203), whose name Tolkien translated as “blood of stone”, and described as “a plant of the kind called in English ‘stonecrop’; it had flowers of a deep red” (UT/148). This word is a combination of sereg “blood” and gond “stone” (SA/gond, sereg).