inestimable (adj.) Look up inestimable at
late 14c., "beyond estimation or measure, not to be computed," from Old French inestimable "priceless" (14c.) or directly from Latin inaestimabilis "invaluable, incalculable," also "not estimable, valueless," from in- "not, opposite of" (see in- (1)) + aestimabilis "valuable, estimable," from aestimare (see esteem (v.)). Meaning "too precious to set a value on, priceless" is attested by 1570s. Related: Inestimably; inestimability.