invaluable[in val′yo̵̅o̅ ə bəl]
The friendship between these two girls is invaluable.
The definition of invaluable is priceless or having value too great to measure.
An example of invaluable is the sentimental worth of your great grandmother's wedding band.
extremely valuable; having value too great to measure; priceless
Of inestimable value; priceless: invaluable paintings; invaluable help.