f, l, p, u are letters that make 'fluff up'
up, luff, fluff, FL, flu, Lu are words within 'fluff up'
1 possible definitions for 'fluff up'
Under this definition, fluff up is a verb and has the following properties:
plump up, shake up have the same meaning as 'fluff up'
'fluff up' can be a type of shake, agitate.
"fluff up the pillows"