It could be aunt, taut.
Some 4 letter words with 'au' in the middle:FauxHaulMaulTautSee the related link for a full list.
faults
au as in orangeo as in bone
There are 4 syllables. Au-to-ma-tion.
Envy Is A 4-Letter Word
The word automobiles has four syllables. The syllables are au-to-mo-BILES. The stress is on the last syllable.
Salt is a 4 letter word for seasoning.
4 letter word for final
4 letter word for drum is "Dhol".
this
There are six syllables. Au-to-mat-i-cal-ly.
You use 'au' to say 'to the' or 'at the' before a masculine word.