before vowels pyr-, word-forming element form meaning "fire," from Greek pyr (genitive pyros) "fire, funeral fire," also symbolic of terrible things, rages, "rarely as an image of warmth and comfort" [Liddell & Scott], from PIE root *paewr- "fire." Pyriphlegethon, literally "fire-blazing," was one of the rivers of Hell.
word-forming element meaning "excessive or irrational fear, horror, or aversion," from Latin -phobia and directly from Greek -phobia "panic fear of," from phobos "fear" (see phobia). In widespread popular use with native words from c. 1800. In psychology, "an abnormal or irrational fear." Related: -phobic.
<a href="https://www.etymonline.com/word/pyrophobia">Etymology of pyrophobia by etymonline</a>
Harper, D. (n.d.). Etymology of pyrophobia. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/pyrophobia