Adjectives ending with the letter B are listed in this post.
acerb
drab, dumb
ebb
glib
lynch-mob
numb
plumb
scrub, sib, slab, squab, superb, syb
undershrub
Hope this word list had the adjective that ends in B you were looking for. Additional descriptive words can be found in the other pages on this site.
Please add more adjectives to make this list more complete: