bad
callous
calloused
cartilaginous
chewy
coriaceous
difficult
enured
fibrous
gristly
hard
hard-bitten
hard-boiled
hardened
hempen
inured
leathered
leatherlike
leathery
pugnacious
rubbery
rugged
sinewy
stringy
thickened
tough-minded
tough-skinned
unchewable
uncomfortable
unsentimental
violent
weather-beaten
Antaeus
Atlas
Briareus
Brobdingnagian
Charles Atlas
Cyclops
Goliath
Herculean
Hercules
Mafioso
OK
Polyphemus
Samson
Spartan
Spartanic
Superman
Tarzan
Titan
Young Turk
abiding
abstruse
ace-high
acute
adamant
adamantine
adherent
adhesive
age-long
aged
amylaceous
ancient
antique
arbitrary
arduous
astringent
athletic
austere
authoritarian
backbreaking
baffling
bang-up
battler
beast
beldam
belligerent
belted knight
berserk
berserker
beyond one
combatant
fighter
scrapper
toughed
nice
rough
smart
ugly
Slough
bluff
bruff
buff
cuff
duff
enough
fluff
gruff
guff
hough
huff
luff
muff
pluff
puff
rebuff
ruf
ruff
scuff
shuff
slough
snuff
stuff
tuff