winner-take-all

Short definition from Wiktionary

Adjective

1. 1
   Of or pertaining to a contest, election, or other competition in which only the winner is rewarded and none of the losers receive anything.
2. 2
   Of a market in which a product or service that is only slightly better than its competitors receives a disproportionately large share of revenue.
3. 3
   Of a neural network model: organized so that neurons in a layer compete with each other for activation.
4. 4
   Alternative form of winner-take-all.