Most common answer: book
Other possible answers:
bait
bead
bean
beat
beer
bibs
blob
bomb
bowl
buds
bugs
bulb
then
Jack
Into.
A four letter word that starts with J and ends with M: jism.
What?
as to
A four letter word that starts with g and ends with n is gown :)
One word that fits this definition is aria.
bend..........
TourTintTiltTimeTameTankToneTuneTentTrueTrim
MeatMateMakeMindMineMintMoodMeekMaleMailMassmast
NounNumbNiceNeatNestNameNailNote