:5001367 There should be a word for that...
For example, take chromosome abnormalities. Down syndrome is considered "common" ("by far the most common chromosomal abnormality") when compared with Edwards syndrome (rare, more so in live births).
We had a little girl on our ward with the latter. I remembered her name, so I was able to find it on a lifespan report. She lived 9.3 years. It's very rare.
Quote source: Scitable by NatureEducation.