unbreakable

adjectives

impossible to break especially under ordinary usage
"unbreakable plastic dinnerwear"
unbreakable
is derived from
unbreakableness
antonym
breakable
is similar to
difficult or impossible to break or separate into parts
"an infrangible series"
infrangible
is similar to
resistant to shattering or splintering
"shatterproof automobile windows"
shatterproof, splinterless, splinterproof
is an attribute of
the consistency of something that breaks under pressure
breakableness