nonundoable
unbeing
nonpotential
good for nothing
as much use as a chocolate fireguard
indefatigability
undepletable
ungained
winning
inavoidable
in vain
nonfailure
undaring
indispensable
questless
luckless
howl at the moon
undefeatable
nonfulfilment
futility
unsucceeding
come to nothing
unpersuasible
formidability
draw a blank
toughness
nonworkable
ineffectively
inefficaciously
incompletable
nonfulfilled
nonprovable
open
meritless
uneasy
careless
swing and a miss
hands-down
unarticulable
handily
Sisyphean
no fear
hands down
attempted
featless