unbreakable

Devotion and gain when linked together will form an unbreakable bond.

The Lhari had an absolute, unbreakable monopoly on star travel.

If this were not an unbreakable rule, no army could endure for a day.

This is an unbreakable circle of false logic that can't be touched.

Between her and the little twice-born son there was an unbreakable tie.

The smooth, unbreakable walls; the thin seam of the door; the thermometer.

It had happened only once before in all history; but the precedent was unbreakable.

The kings of Aquilonia had long learned the worth of unbreakable infantry.

A man, human and humane; devoid of fear, with an unbreakable will.

But perhaps you count that among your unbreakable possessions.