 The words "iu" and "unu" (or their plurals "iuj" and "unuj") may be used somewhat like indefinite articles, but they're closer in meaning to "some" and "a certain" than to English "a".This use of "unu" corresponds to English "a" when the "a" indicates a specific individual.The suffixes "‑o", "‑a", "‑e", and "‑i" indicate that a word is a noun, adjective, adverb, and infinitive verb, respectively.