Yes, that’s the “neutral” term that’s used in the haircare and hair color industry, though there are both ash blondes (I’m one), and ash browns. If you go to the drug store, and browse the hair color aisle, you’ll see a lot of Ash Blonde and Ash Brown shades.
Example pictures (though a lot of ash blondes and ash browns can look pretty similar)
Medium Ash Blonde
Dark Ash Blonde
Light Ash Brown
Medium Ash Brown
The other “non-neutral” term I’ve heard for ash blondes is “dishwater blonde.”