At what point do you consider yourself to be mashing? Is it simply the gear ratio you're in versus the incline or is it the inability to sustain a certain rpm in a gear? I think this is naive on my part (and the lack of knee pain so far) but I feel lazy if I'm not mashing at least part of the time. I'm on the bike partially to strengthen my legs and get a workoutand I certainly feel the burn a lot more the more time I spend in a higher gear.

To me, it's 200w above FT. It's an all-out attempt to get as fast as possible within a short distance.

Anything below a cadence of about 70ish. If you are spinning as slow as grandma on her cruiser, you are doing it wrong.

That's your idea of a "technical" definition?

I think part of the reason I find myself doing it more often then I should is twofold. Even at the highest gear ratio on my old fuji I can get up to speed fairly quickly and comfortably and I'm having to stop so often in nyc traffic that I often forget to downshift first. The watts measurements have me lost at this point. Does that translate to cadence somehow?

Mashing to me = when I know should be in a lower gear. Also see: my feet and ankles hurt.

Just taking it easy and riding at 60 isn't mashing.

technically speaking
mashing is when you can't keep time with your pedal stroke by mouthing "1cat, 2cat, 3cat, 4cat,..."
and it turns into
"1Djamolidine Abdoujaparov, 2Djamolidine Abdoujaparov, 3Djamolidine Abdoujaparov, 4Djamolidine Abdoujaparov,..."
and flies can easily land on your thigh and hang out...

I especially hate it when flies smack into your shades, or worse, straight down your throat (bc you're huffing and puffing so hard).