CentiMorgan (cM)

Explanation:

A centiMorgan(cM) is a measure of genetic linkage and is often used to infer the distance along a chromosome. 1 centiMorgan corresponds to around 1 million base pairs on average but varies depending on the location in the genome. 

Additional resources:

1. https://en.wikipedia.org/wiki/Centimorgan

2. https://www.genome.gov/genetics-glossary/Centimorgan