fodder! fatter
raunch
There could be multiple answers to this. RACISM is one such word starting with R and ending with M.
Scarbeardearfeargearhearnearpearrearseartearwearyear.
appearbrotherchowderdrifteremperorflickerflustergrinderhoarderintegerjanitorlaundrymufflerneitherprinterremoverslenderteachervaulterwhisperyounger
The three-letter word for scull is "oar."
runners
certain
sheriff
Rasta
rancher
hustler
iter