There is no precise definition of superzoom, but lenses marketed as such usually have an optical zoom ratio greater than 7×.
[4] This is a list of lenses designed for full-frame mirrorless cameras that have an optical zoom ratio greater than 7×.
This is a list of lenses designed for APS-C mirrorless cameras that have an optical zoom ratio greater than 7×.
For comparison, the longest superzoom lens designed for DSLRs was the Tamron 18-400mm F3.5-6.3 for EF and F mounts, which had a 22× optical zoom ratio.
[5] This is a list of Micro Four Thirds lenses that have an optical zoom ratio greater than 7×.