the Later Latin Society

a Brief Guide to
Quantity of Syllables
in Latin Prosody

I. Monosyllabic Words (01) all monosyllabic words are long—except (02) enclitics; words ending in b, d or t; and an, cor, bis, cis, es, fac, fel, fer, in, is, mel, nec, os (bone), per, quis (nom.), ter, vel and vir, and sometimes hic are short. II. Final Vowels a (03) final a is usually short (in nominative and vocative singular, neuter plurals, and in eia, ita and quia)—but (04) final a is long in ablative singular of first declension nouns; (05) final a is long in the second singular imperative active of first conjugation verbs; and (06) final a is long in prepositions (a, circa, citra, contra, erga, extra, infra, intra, iuxta, supra and ultra) and in indeclinable words such as frustra, interea, postea, praeterea. e (07) final e is usually short—except (08) final e is long in the ablative singular of fifth declension nouns; (09) final e is long in the second singular imperative active of second conjugation verbs (except in cave where e may be long or short); and (10) final e is long in adverbs formed from adjectives in -us, -a, -um (but note that final e is short in the adverbs bene, inferne, male and superne). i (11) final i is usually long—but (12) final i is short in nisi and quasi; and (13) final i may be short or long in ibi, mihi, sibi, tibi and ubi. o (14) final o is usually long—but (15) final o is short in cito, duo, ego, modo, ordo and quomodo, and sometimes short in homo and nemo. u (16) final u is always long. y (17) final y is always short. III. Diphthongs (18) all syllables containing diphthongs are long—except immediately before another vowel or h; but note Rule 37 below. IV. Disyllables and Polysyllables ending in s as (19) final as is nearly always long (except in anas). es (20) final es is often long—but (21) final es is short in nominative singular of third declension nouns which have a genitive singular in -etis, -itis or -idis (though final es is long in abies, Ceres and paries); (22) final es is short in compounds of es (from sum); and (23) final es is short in penes. is (24) final is is often short—but (25) final is is long in dative and ablative plurals; (26) final is is long in nominative and accusative plurals of -i stem third declension nouns; and (27) final is is long in the second personal singular of fourth conjugation verbs; (28) final is is long in is (from eo) and in malis, nolis, sis (and compounds of sis) and velis; and (29) final is may be long or short in the future perfect and perfect subjunctive. os (30) final os is almost always long—except (31) final os in compos, exos and impos is short. us (32) final us is usually short—but (33) final us is long in genitive singular and in nominative, accusative and vocative plurals of fourth declension nouns; and (34) final us is long in the nominative singular of consonant stem third declension nouns having a genitive singular with a long penultimate syllable. ys (35) final ys is short. V. Syllables Ending with Vowels (36) a syllable ending with any vowel or diphthong which is immediately followed by a vowel, or with h and a vowel, is short—but (37) monosyllabic interjections are not elided and remain long; and (38) the i is long in dius and in genitives of pronouns in -ius (though the second i in illius and ipsius may be long or short, and the i is always short in alterius); (39) e is long in ei of fifth declension nouns; (40) e is long in ei (from is); and (41) i is long in forms of fio (except before -er, as in fieri). VI. Syllables Ending with Two Consonants (42) a syllable containing a vowel followed by two consonants or by x or z is long—but (43) if a short vowel precede bl, br, cl, cr, dr, fl, fr, gr, pl, pr or tr, then the syllable need not be long. VII. Final syllables Ending with Syllables Other than s (44) final syllables of words of more than one syllable ending with one consonant other than s are short—but (45) the final syllable in allec, lien, many Greek substantives, illuc, posthac, in compounds of par, in the perfects iit and petiit is long; and (46) final -at, -et and -it are occasionally long before a pause in the classical poets. VIII. Final Syllables before Words Beginning with Consonants (47) a final syllable ending with a short vowel and a consonant is long by position if the next word begin with any consonant; but (48) a final syllable ending with a short vowel remains short even if the next word begin with two consonants. IX. Greek Words (49) Roman poets sometimes use the Greek pronunciation of Greek words, and often use the Greek pronunciation of Greek names (thus, for instance, allowing a vowel to be long before another vowel, as in âĕr and Aenêâs). X. A Warning (50) poets have been known to break rules.

see also the Declension of Greek Substantives in Latin.