The rules for positioning of syllable stress in Latin are relatively simple; they are as follows:

  1. In two-syllable words, the stress always falls on the first syllable.

  2. In three or more syllable words, the stress falls like so:

    a. If the penultimate (second-to-last) syllable is heavy, the stress is placed on it.

    b. If the penultimate syllable is light, the stress is placed on the antepenultimate (third-to-last) syllable.

This alone is all well and good, there are only three-ish rules to memorize, and the irregular couple-syllable words that are exceptions to this rule are easy to learn and recognize. However, what always trips me up is the use of the terms "heavy" and "light" (or other related terms) to describe which syllables are stressed.

For the duration of my Latin learning experience, I have simply assumed that syllables containing long vowels were heavy and that syllables containing short vowels were light, or simply just making a qualitative judgment to determine whether the penultimate or antepenultimate syllables "felt" heavy or light. Neither of these methods has ever felt sound to me and I am almost 100% certain that I am not distinguishing heavy and light syllables correctly. Thus, my question:

What are the differences between heavy and light syllables and how does one go about identifying them?

  • 1
    You have given a clear description of stress: there can only be one stressed syllable in a given word; I believe that there is a further rule that a prefix (in- dys-) cannot be the stressed syllable. However in metrication a spondee, for instance, consists of two consecutive heavy syllables, sometimes in one word. Well-formed Latin seems to have used stress and heavy-light in some sort of interplay. Additionally, tho' I've not seen it argued, terminal vowel followed by initial vowel; and terminal vowel+m followed by vowel, elision, seem to be used where there is excitement, panic, fear – Hugh Sep 20 '18 at 0:44
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    @Hugh I've never seen a rule that prefixes can't be stressed -- do you have a source for it? – TKR Sep 20 '18 at 18:41
  • @ TKR : you're right. "Incipit" for a start. – Hugh Sep 20 '18 at 21:02

A syllable is heavy if it has a long vowel (or diphthong), or if it ends in a consonant—-although the consonant rule had some exceptions in old poetry.

Latin syllabification for intervocalic consonant clusters

Figuring out if a syllable ends in a consonant can be a bit tricky. Almost all consonant clusters in Latin were split between syllables when they occurred in between vowels in the middle of a word. This includes double (also called "geminate") consonants, and it also includes -sp-, -st-, sc-. So words like sinister, minister, magister were stressed on the second-to-last syllable in Classical Latin.

One complication is that Latin didn’t always write double consonants with two letters (Z and most intervocalic I/J scan as double consonants, despite being written with only single letter).

The exception to the rule that word-internal intervocalic consonant clusters were split between syllables consists of “mute + liquid” clusters, composed of an obstruent followed by R or L (e.g. tr, pr, cr, br, cl, ...). These could either be split between syllables (in which case the preceding syllable would be heavy), or could occur at the start of a syllable (in which case the preceding syllable would be light).

As Joonas mentions, QU is also an exception if you analyze it as a consonant cluster (it can also be analyzed as a unitary sound /kʷ/).


A syllable is can be heavy in two ways. It is heavy by nature if it contains a long vowel or a diphthong. It is heavy by position if the vowel is followed by a "consonant cluster". If neither happens, the syllable is light. It can also be heavy for both of the two reasons.

The irregularities have to do with what "consonant cluster" means. Mostly, it means two or more consonants, and simplifying the rule this way gets most cases right. The important question is whether the consonant or combination thereof sounds short or long. Some long-looking combinations of consonants are short and do not count as "consonant clusters" for syllable weight; these are qu and some cases of muta cum liquida. Sometimes a "consonant cluster" is spelled with a single letter, like the i in maior (pronounced /majjor/, not /major/ or /maajor/) or z. Perhaps a more accurate term would have been "long consonant sound" rather than "consonant cluster".


The answer to your question is simple and difficult at the same time.

As Christian Lehmann (Lehmann 2010) puts it rather succinctly,

"A light syllable is one ending in a short vowel; all other syllables are heavy."

The real challenge, of course, is syllabification, i.e. how to correctly (best?) divide any Latin word into syllables, e.g. rēg.num or rē.gnum? (the latter is most likely since a consonant cluster cannot follow a long vowel or diphthong) - although Lehmann argues that "Latin’s syllabication rules are very simple."

He mentions two rules:

  1. Except at the beginning of a breath group, a syllable onset must contain at least one segment.
  2. From there, the left syllable boundary is shifted successively leftward until either sonority no longer decreases sufficiently or there is a grammatical boundary (Lehmann 2010).

I am afraid the minutiae of syllabification in Latin would be of particular interest to theoretical linguists mostly and I don't see much practical use in discussing specific contexts and words (e.g. vólu.cres vs. volúc.res or re.flecto vs. cinif.lones; Weiss pp.67-71 is a good place to start with). However, if you would like to know more about syllabification in Latin, perhaps a separate question would be better.

  • With rule 1), what is the treatment of vowels that seem to be in hiatus? – sumelic Sep 21 '18 at 5:54
  • @sumelic What exactly did you have in mind? A specific example would be more helpful. (it could be rule 1 - it says "one segment in a syllable onset" or rule 2 "there is a grammatical boundary") – Alex B. Sep 21 '18 at 15:20
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    @sumelic a quote for you from Lehmann 2005: "A sequence of two vowels that contains a morpheme boundary (V#V) is always separated by a syllable boundary (re#i, re#um, me#am, tu#us etc.). If there is no morpheme boundary between two vowels, the sequence would be contracted into a diphthong, in other words, one of the two vowels would become a semivowel." – Alex B. Sep 21 '18 at 16:22
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    Thanks; I hadn’t noticed before that hiatus in Latin occurred mainly across morpheme boundaries. – sumelic Sep 21 '18 at 20:11
  • But still, I don’t think the second syllables of “meam” etc start a new breath group, do they? Also, I’m confused about the argument against “reg.num” because it seems to me that in “rex” we have a long vowel followed by a consonant cluster. – sumelic Sep 21 '18 at 20:16

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