I've been learning Italian recently just by myself on a very casual basis. One thing that I find confusing is which syllable to stress. I've read the rules - i.e. usually the penultimate syllable is stressed, unless there is an accent mark on the last syllable. However, there are many, many examples where the third-from-last syllable is stressed instead. So, for example, when I see a word like telefono, or illeggibile, how can I tell that it's the third-from-last syllable that is stressed, and not the penultimate one?
For a number of word endings the stress is predictable. For instance, all superlative forms in -issimo are “sdrucciole” (i.e., stressed on the third-from-last syllable): bellìssimo, velocìssimo and so on. The same holds for most moods and tenses of verbs, and suffixes, and other regular modifications of words. You can find many of them in the online Dizionario di Ortografia e Pronunzia, under “Suffissi”, “Desinenze grammaticali” and “Terminazioni con varianti di forma”.
As for single words themselves, short of knowing well their etymology (and often even then), there is no alternative to looking them up in a good dictionary. Italians themselves often have to do so (and Italians themselves often get a stress wrong).
As for your particular examples:
illeggibile falls within the “predictable” case: -abile, -ibile suffixes denote something that “can be done” (leggere = to read; leggere + -ibile = leggibile = readable; in your case the prefix in- negates this, yielding the meaning of “unreadable”) and they are always stressed on the third-from-last syllable;
telefono, on the contrary, like some modern formations from Latin and Greek roots, is a mess. Compare telèfono with telescòpio, or motoscàfo and piròscafo, for instance. You have to just look them up, unfortunately.
;-)– egreg ♦May 2, 2016 at 8:32
1Thanks for your thorough and helpful answer. It's a pity that some Italian words require guesswork, and I wonder why, since the Italians have an accent mark, they don't use it for syllables other than the last one. Other European languages have unambiguous pronunciation. For example, my first language is Greek, and that has an accent on every stressed syllable (except monosyllabic words) so it's always clear which syllable is stressed. Spanish also has rules that make the stress unambiguous. French completely avoids the issue by not having stress, and English avoids the issue by being a mess. May 2, 2016 at 9:18
@KlitosKyriacou French pronunciation is not unambiguous. See, for instance, the large number of exceptions here: blogs.transparent.com/french/… May 2, 2016 at 9:25
1@FedericoPoloni that is indeed true. One thing that gets me is ll in French is sometimes pronounced as a y, but not always. But here I was specifically talking about ambiguity in stress, rather than in pronunciation in general. May 2, 2016 at 9:54
2@KlitosKyriacou It's not that bad. Most of the words fall into the predictable category. I'd say that Italian pronunciation is more or less on par with the French as predictability (French most definitively has stress). Generally speaking the accent can be only in three positions: the last syllable, the second to last or the third to last. The first case is graphically indicated (e.g. più, città, però...) and the third case is relatively uncommon and mostly accounted for by predictable words. Yeah there are a few weird common words but I don't think it's worse than most languages.– Denis Nardin ♦May 2, 2016 at 12:39
Jakub Marian (https://jakubmarian.com/stress-position-and-accents-in-italian/) provides the following suffixes to help with determining the stressed syllable.
-agine, -aggine, -igine, -iggine, -edine, -udine, -abile, -evole, -ibile, -ico, -aceo, -ognolo, -oide, -cefalo, -crate, -dromo, -fago, -filo, -fobo, -fono, -gamo, -geno, -gono, -grafo, -logo, -mane, -metro, -nomo, -stato, -tesi, -ttero, -fero, -fugo, -voro
If an Italian word ends in one of these suffixes, it is likely to be stressed on the antepenultimate syllable.
Other than that, and the grave accent stressing the last syllable of a word, you'll have to use a dictionary.
1Welcome! Can you please complete your answer giving some more details? In the way it's now it doesn't seem very useful.– Charo ♦Jan 5 at 12:45