Mediocre-of only ordinary or moderate quality; neither good nor bad; barely adequate.
arsonist-
noun a person who commits arson
.
treason - the offense of acting to overthrow one's government or to harm or kill its sovereign.
loam - a rich, friable soil containing a relatively equal mixture of sand and silt and a somewhat smaller proportion of clay.
praetorian - of or pertaining to a praetor.
centrifuge - an apparatus that rotates at high speed and by centrifugal force separates substances of different densities, as milk and cream.
Antaeus - an African giant who was invincible when in contact with the earth but was lifted into the air by Hercules and crushed.
Insidious - intended to entrap or beguile:
an insidious plan.
Harlequin - a comic character in commedia dell'arte and the harlequinade, usually masked, dressed in multicolored, diamond-patterned tights, and carrying a wooden sword or magic wand.