toughened Synonyms
tough
hardened
treated
tempered
thick-skinned
temper
sturdy
strong
strengthen
strengthened
stiffen
stiffened
stiff
steeled
make more severe
toughening
make stricter
shatterproof
nonbreaking
galvanised
hard-boiled
case-hardened
calloused
bulletproof
reinforced
tighten up
armoured
solidified
solid
set
fortify
fortified
firm
experient
experienced
dura
callous
braced
bombproof
armored
annealed
hard
harden
hardy
seasoned
rugged
roughened
resistant
reinforce
obdurate