A link bt.Victor Fet's
information about the botanical and zoological "dracunculi" (ADA), that leads
into Sklyarenko's "rankle" (LATH) which might deserve an annotation
in Brian Boyd's AdaOnline!
Proto-Indo-European *derḱ- "to see" became
Greek δέρκομαι "to see clearly", and δράκων "dragon, serpent" - "from his
supposed sharp sight" says Skeat. Δράκων was borrowed into Latin as dracōnem
becoming French dragon.
Δράκων was borrowed into Arabic as طرخون ṭarẖwn, a
name for tarragon, also known as dragonwort, Latin name Artemisia dracunculus.