underfilled 

something that is lacking - metaphorically and/or physically. (Term popularized by @thekatcurtis)

“This bag of chips is more air than chips - it’s UNDERFILLED!!”

underfilled by funwitfunny March 16, 2022

underfile

other party in a pedo relationship

guy1: isnt she dating a 20 yr old
guy2: yah shes so an underfile

underfile by heart.break.breakfast. November 25, 2010

Unforfilled 

A word a moron wrote on a bathroom stall

Trying to be deep "unforfilled" can't spell unfulfilled

Unforfilled by Pissed off Amazon guy March 8, 2021