multisyllabic
Having many syllables. Butterfly is a multisyllabic word.
schwa
The lazy, quiet vowel sound "uh", like the a in about or both a's at the end of Canada.
stress
The syllable you say a little louder and longer, like the middle of fan-TAS-tic.
flex
To try a different sound for a letter or a different stress when your first try doesn't make a real word.
approximation
A first try at a word that is close but not quite right.