amoebas
trouble
abbigal
cabinetcaboosedebtorsrebuiltonboardmobsterreboundsubsidywebsitetabletssubwayslobsterreboundrebateslibraryrabbitsdebrieffibbingembraceembargolabeledorbitedrebirth
nabobs
bunting
bathtub, brewpub
Some seven letter words starting with B are:bathtubdisturbperturbproverbrhubarbsuccumbtaxicabwashtub
There is no 7-letter word using those letters, but there are two 6-letter options:confabforbad
cobbler
babysit
cribbed
besides