4. Final o is regularly long, but is short:—
a) In egŏ, duŏ, modŏ (only), citŏ.
b) Rarely in the First Person Singular of the Verb, and in Nominatives of the Third Declension; as, amŏ, leŏ.
c) In a few compounds beginning with the Preposition pro, especially before f; as prŏfundere, prŏficīscī, prŏfugere.
5. Final u is always long.
B. Final Syllables ending in a Consonant.
[364]. 1. Final syllables ending in any other consonant than s are short. The following words, however, have a long vowel: sāl, sōl, Lār, pār, vēr, fūr, dīc, dūc, ēn, nōn, quīn, sīn, sīc, cūr. Also the adverbs hīc, illīc, istīc.[[60]]
2. Final syllables in -as are long; as, terrās, amās.
3. Final syllables in -es are regularly long, but are short:—
a) In the Nominative and Vocative Singular of dental stems ([§ 33]) of the Third Declension which have a short penult in the Genitive; as, segĕs (segetis), obsĕs (obsidis), mīlĕs, dīvĕs. But a few have -ēs; viz. pēs, ariēs, abiēs, pariēs.
b) In ēs (thou art), penēs.
4. Final -os is usually long, but short in ŏs (ossis), compŏs, impŏs.
5. Final -is is usually short, but is long:—