adjective
unbreakable
un-BRAY-kuh-bul/ʌnˈbreɪkəbl/
Impossible or very difficult to break.
The nearly unbreakable steel link remains intact under opposing forces.

Etymology
The negative prefix denies the possibility expressed by break plus -able. Breaking need not mean physical damage: the earliest cited use concerns a law that could not be broken.
In context
the genuine, unbreakable trust of a true son, tested to the limit and found solid.
More examples
- No phone screen is truly unbreakable.
- Their years of friendship create an unbreakable bond.
- She treats her promise as an unbreakable commitment.
Forms
unbreakable
breakable adjective — Capable of being cracked or broken.
Similar words
- shatterproof
- Specifically resists shattering into pieces, especially glass or plastic.
- durable
- Withstands wear over time, not necessarily sudden force.