upper boundary

https://doi.org/10.1351/goldbook.16179
Estimate of the plausible upper limit to the true value of a quantity.
Note: This is usually not a statistical confidence limit.
Source:
PAC, 2007, 79, 1153. (Glossary of terms used in toxicology, 2nd edition (IUPAC Recommendations 2007)) on page 1331 [Terms] [Paper]