difficult
hard
superhuman
Antaean
Atlantean
Briarean
Brobdingnagian
Cyclopean
Gargantuan
Homeric
abstruse
abysmal
arduous
astronomic
backbreaking
brutal
burdensome
colossal
complex
critical
crushing
delicate
demanding
difficile
effortful
elephantine
enormous
epic
exacting
forced
formidable
gargantuan
giant
giantlike
gigantic
grueling
hairy
hard-earned
hard-fought
heavy
hefty
heroic
huge
immense
infinite
intricate
jawbreaking
jumbo
killing
knotted
knotty
back-breaking
barrel-like
daunt
ill-paid
menial
monumental
persevering
praiseworthy
sinewy
stupendous
thankless
titanic
toilsome
unremitting
unrequited
unrewarded
unwearied
well-knit
Julian