There were several restrictions on phonotactics and the shape of the PA word that can be reconstructed. All words began with a single consonant (other than *h) or vowel, or with a consonant plus *w or *y; there were no sequences of consecutive vowels; and the word always ended in a short vowel. The vowels *i and *o never occurred in initial syllables. A sequence of consonant+semivowel could not be followed by *o or *o·. There was also a restriction which prevented two-syllable nouns from ending in a sequence of short vowel + consonant + short vowel.
