14. Latin, the language of the ancient Romans, was properly, as its name implies, the language spoken in the plain of Latium, lying south of the Tiber, which was the first territory occupied and governed by the Romans. It is a descendant of an early form of speech commonly called Indo-European (called by some Indo-Germanic), from which are also descended most of the important languages now in use in Europe, including among others English, German, the Slavic and the Celtic languages, as well as some now or formerly spoken in Asia, such as Sanskrit, Persian, Armenian. Greek likewise belongs to the same family. The Romance (or Romanic) languages, of which the most important are Italian, French, Provençal, Spanish, Portuguese, and Roumanian, are modern descendants of spoken Latin.

The earliest known forms of Latin are preserved in a few inscriptions. These increase in number as we approach the time when the language began to be used in literature; that is, about 250 B.C. It is the comparatively stable language of the classical period (80 B.C. - 14 A.D.) that is ordinarily meant when we speak of Latin.

15. Among the main features in the changes of Latin from the earliest stages of the language as we know it up to the forms of classical Latin may be mentioned the following:

Vowel Changes

1. The old diphthong ai became the classical ae (aedīlis for old aidīlis), old oi became oe or ū (ūnus for old oinos), and old ou became ū (dūco for old doucō).

2. In compound verbs the vowel a of the simple verb often appears as i or e and ae similarly appears as ī.

   faciō, factum BUT cōnficiō, cōnfectum
   caedō BUT occīdō

   Similarly
   cecīdī, perfect of caedō
   (cf. cadō, occidō; cecidī, perfect of cadō).

   Note— This change is commonly ascribed to an accentuation on the first syllable, which seems to have been the rule in Latin before the rule given above (see § 12) became established. The original Indo-European accent, however, was not limited by either of these principles; it was probably consisted of a change in pitch, and not merely in a more forcible utterance of the accented syllable

3. Two vowels coming together are often contracted.

   cōgō for †coagō
   prōmō for †proemō
   nīl for †nihil
   dēbeō for †dēhibeō

   Consonant Changes

4. An old s regularly became r between two vowels (rhotacism), passing first through the sound of (English) z.

   eram (cf. est)
   generis, genitive of genus¹

   Note— Final s sometimes became r by analogy; as honor (older honōs), from the analogy of honōris.

5. A dental (t, d) often became s, especially when standing next to t, d, or s.

   equestris for †equettris
   cāsus for †cadtus (cf.  6., below)

6. Many instances of assimilation, partial or complete, are found.

   cessī for †cedsī
   summus for †supmus
   scrīptus for †scrībtus (b unvoicing to p before the voiceless t)

   Assimilation is also found in compound verbs (see § 16).

   Dissimilation, the opposite kind of change, prevented in some cases the repetition of the same sound in successive syllables.

   palīlia (from Palēs);
   merīdiēs for medīdiēs,
   nātūrālis with suffix -lis (after r)

   BUT
   populāris with -āris (after l)

7. Final s was in early Latin not always pronounced, as in  plēnu(s) fidēī.

   Note— Traces of this pronunciation existed in Cicero's time. He speaks of the omission of final s before a word beginning with a consonant as "countrified" (subrūsticum).

8. A final consonant often disappears.

   virgō for †virgon
   lac for †lact
   cor for †cord

9. G, c and h unite with a following s to form x.

   rēx for †rēgs
   dux for †ducs
   trāxī for †trahsī²

10. G and h before t became c.

    rēctum for †rēgtum
    āctum for †agtum
    trāctum for †trahtum³

11. Between m and s or m and t, a p is often developed.

    sūmpsī for †sūmsī
    ēmptum for †ēmtum

16. In compounds with prepositions the final consonant in the preposition was often assimilated to the following consonant, but usage varied considerably.

• There is good authority for many complete or partial assimilations:  ad, acc-, agg-, app-, att-, adc-, adg-, etc.
• Before a labial consonant we find com- (comb-, comp-, comm-), but con- is the form before c, d, f, g, consonantal i, q, s, t, and consonantal v; we find conl- or coll-, conr- or corr-; cō- in cōnectō, cōnīveō, cōnītor, cōnūbium.
• In usually changes to im- before b, m.
• Ob and sub may assimilate b to a following c, f, g, or p; before s and t the pronunciation of prepositions ending in b doubtless had p; surr-, summ-, occur for subr-, subm-.
• The inseparable amb- loses b before a consonant.
• Circum often loses its m before i.
• The s of dis becomes r before a vowel and is assimilated to a following f; sometimes this prefix appears as dī-.
• Instead of ex we find ef- before f (also ecf-).
• The d of red and sēd is generally lost before a consonant. The preposition is better left unchanged in most other cases.

Vowel Variations

17. The parent language showed great variation in the vowel sounds of kindred words.⁴

a. This variation is often called by the German name Ablaut. It has left considerable traces in the forms of Latin words, appearing sometimes as a difference of quantity in the same vowel (as, u, ū; e, ē), sometimes as a difference in the vowel itself (as, e, o; i, ae).⁵

tegō  I cover, toga  a robe
pendō  I weigh, pondus  weight
fidēs  faith, fīdus faithful, foedus  a treaty
miser  wretched, maestus  sad
dare  to give, dōnum  a gift
regō  I rule, rēx  a king
dux  a leader, dūcō (for older doucō)  I lead

Compare English drive, drove (drave), driven; bind, bound, band; sing, sang, sung; etc.