13-Letter Words Ending in DES

There are 40 13-letter words that end in DES. 4 are common words, such as FORMALDEHYDES and MOUNTAINSIDES. A rarer one is TONSILLITIDES. In this set, I is the most frequent open letter (32 words). 6 words contain a doubled letter.

Full list 40

Common words

formaldehydesmountainsidespharyngitidestriglyceridesacetaldehydesblepharitidescorrectitudesdisaccharidesferricyanidesferrocyanidesharlequinadesinexactitudes
formaldehydesmountainsidespharyngitidestriglyceridesacetaldehydesblepharitidescorrectitudesdisaccharidesferricyanidesferrocyanidesharlequinadesinexactitudesmastoiditidesphotocathodesbenzaldehydeschalcogenidescountertradesdegringoladesdinucleotidesendoperoxidesglutethimidesglycopeptidesmethysergidesmolluscicidesneuropeptidesnicotinamidesoverpersuadesparasiticidespentapeptidesperiostitidesperitonitidespneumonitidesprostatitidespseudomonadesradionuclidesrhodomontadessalpingitidesspondylitidesthyroiditidestonsillitides

About this list

Words
40 (4 common words)
Common example
formaldehydes
Rare example
tonsillitides
Doubled letters
6
Ending in S
40
Most frequent letter
I (32)

Questions

How many 13-letter words ending in des are there?

40. 4 of them are common words.

What is a common example?

FORMALDEHYDES is among the common words in this set.