collisional

adjective

col·​li·​sion·​al kə-ˈlizh-nəl 

-ˈli-zhə-nᵊl

: marked by or ensuing from a collision

collisionally adverb

The Kuiper Belt is … collisionally evolving, meaning that the region's icy content has been modified over the past 4.5 billion years, since the solar system was born.

—Space.com, 29 Dec. 2009

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