Agreed it could have a better name and description; I was initially trying to stay very close to the naming/description from the C version, and the minimalism of existing descriptions. 

There's an additional bit of subtlety in that, unlike the impression given by some of the C word2vec docs, this is *not* the exact frequency threshold over which some words are subsampled. Rather, this is a parameter to the subsampling formula, and the actual frequency where sampling-probability goes below 1.0 is about 2.6x this parameter.

So maybe 'subsample_denominator'? (I don't recognize the formula being used, but assuming it's well-known in the domain, and that parameter is traditionally named  `foo`, then perhaps something like `subsample_foo`?)