is there such a word as ελπιδων?
M. Unit 28.I.8, p.241: “…ουτοι γαρ ουχ ημαρτον των ελπιδων,…” I would have expected “ελπιζων”. I can’t find any word beginning with ελπιδ… Where am I wrong? (I’m sure I am, as usual 
)
Thank you.
The word is ἐλπίς, nom. sing. fem. (hope).
See page 117 of Mastronarde for the declension with ἀσπίς as the model.
This is a pretty common pattern that you’ll want to get used to seeing. You have a noun that has a certain nominative singular, and then the genitive and the other forms add a δ.
Any time you’re stuck like this, you also have the option of just typing the word in at https://en.wiktionary.org/ or http://logeion.uchicago.edu/ , and usually they’ll tell you what dictionary form your word comes from.
Thank you, Katalogon and Ben,
Yes, of course! The sentence is an exercise about participles and I thought that word was a misspelling of the participle. which it isn’t. Hence my error.