invaluable

If you're robbed, much of what is stolen can be replaced. All you need is the cash value of what was lost. But some things––family photos, heirloom jewelry––are invaluable, meaning extremely valuable, or priceless.

At first glance, you would think that invaluable means "not valuable." But to understand its meaning, you'd have to know that it was formed from the prefix in- "not" plus the verb value, plus the suffix –able "able to be." So something invaluable has such great value that its value can't be calculated.

Definitions of invaluable
1

adj having incalculable monetary, intellectual, or spiritual worth

Synonyms:
priceless
valuable
having great material or monetary value especially for use or exchange