whew
exclamation
hwjuː 
hwjuː fjuː fjuː a sound that people make to show that they are surprised or relieved about something or that they are very hot or tired
Whew—and I thought it was serious!Ten grand? Whew! compare phew
Definition of whew exclamation from the Oxford Advanced Learner's Dictionary
hwjuː hwjuː fjuː fjuː 