Unbreakable means impossible to break in normal use. Unbreakable glass, an unbreakable bond, an unbreakable record.
The qualification is always there in practice, since unbreakable glass means it survives being dropped rather than anything at all. Of a promise or a record it means nothing has broken it yet.
1adjectiveunbreakableImpossible to break in normal use.
“The toddler's plates are made of unbreakable plastic, so he can't smash them.”
unbreakable is a quality.
Middle English
breken
English
break
English, today
unbreakable
From un- + break + -able. break comes from Middle English breken. From Middle English breken, from Old English brecan (“to break”), from Proto-West Germanic brekan, from Proto-Germanic brekaną (“to break”), from Proto-Indo-European bʰreg- (“to break”). a doublet of bray. 2
Etymology from Wiktionary, CC BY-SA