Classical Nahuatl grammar

The grammar of Classical Nahuatl is agglutinative, head-marking, and makes extensive use of compounding, noun incorporation and derivation. That is, it can add many different prefixes and suffixes to a root until very long words are formed. Very long verbal forms or nouns created by incorporation, and accumulation of prefixes are common in literary works. New words can thus be easily created.

Vowel length was phonologically distinctive in Classical Nahuatl, but vowel length was rarely transcribed in manuscripts, leading to occasional difficulties in discerning whether a given vowel was long or short. In this article, long vowels are indicated with a macron above the vowel letter: <ā, ē, ī, ō>. Another feature which is rarely marked in manuscripts is the saltillo or glottal stop ([ʔ]). In this article, the saltillo is indicated with an h following a vowel. The grammarian Horacio Carochi (1645) represented saltillo by marking diacritics on the preceding vowel: grave accent on nonfinal vowels <à, ì, è, ò> and circumflex on final vowels <â, î, ê, ô>. Carochi is almost alone among colonial-era grammarians in consistently representing both saltillo and vowel length in transcription, even though they are both essential to a proper understanding of Classical Nahuatl.

The phonological shapes of Nahuatl morphemes may be altered in particular contexts, depending on the shape of the adjacent morphemes or their position in the word.

Where a morpheme ending in a consonant is followed by a morpheme beginning in a consonant, one of the two consonants often undergoes assimilation, adopting features of the other consonant.

Almost all doubled consonants in Nahuatl are produced by the assimilation of two different consonants from different morphemes. Doubled consonants within a single morpheme are rare, a notable example being the verb -itta "see".

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