> I guess viscosity because “consistency” has other connotations and if anything they seem to be more consistent.

You're thinking of two different words.

https://www.merriam-webster.com/dictionary/consistency

Sense 1: agreement of parts or features to one another or a whole

Sense 2: degree of firmness, density, or viscosity

Notably, sense 1 has a related adjective, consistent, and sense 2 does not.