Incoherent Memoirs

A bumper crop of Lovecraftian erudition in 'The Dunwich Horror' : Where something is "teratoligically" impossible, 'teratological' means   " abnormal in growth or structure" (w hich certainly fits the Whateley offspring). If something (Wilbur Whateley's skin for example) is "cilated" this means it's covered in microscopic projections which look like hairs. "Acherontic" fear is meant to evoke something "as dark and dismal as the river Acheron" , the 'river of fear', in Hades (akin to the river Styx). And last but by no means least: "eldritch" ! One of those words which HPL uses frequently, and very famously, though I only really know it through usage and context. Sure enough, it simply means "weird and sinister or ghostly" .

'The Shadow Out of Time ' presents us with The Great Race, who amongst other things have a language composed of "agglutinative" speech. This is very specific, for the definition, I find, is  that this kind of speech " expresses concepts in complex words consisting of many elements, rather than by inflection  or by using isolated elements" . Given that the Great Race are totally non-human beings who resemble "rugose" cones ( "wrinkled, corrugated" ) this is not terribly helpful. One for the 'HPL doing his best to express an inexpressible concept' list!