Preantepenultimate syllable

From Teflpedia

A preantepenultimate syllable is a syllable in found in a tetrasyllabic (or greater) word that precedes the antepenultimate syllable, the penultimate syllable and its final syllable.

In English, many adverbs are typically stressed on this syllable. For example, "considerably" oOooo.

Exceptions are mostly adverbs that contain -tion, these tend to end -tionately, and are stressed on the syllable before -tion, which is the antepenultimate syllable.