anil -- the indigo plant or the blue dye obtained from this plant.
There may be others.
Four letter adjectives that begin with the letter f:fairfakefastfinefiveflatfoulfourfreefull
envy
Utah
onlyonceomenopenomitoverontoovidovum
lute
spud
Audi
junk
Four...
zeal.
Snidely Spellbinder wrote a four-letter word that begins and ends with e. With ease.
nabs