"reasonless" in the adjective sense
1. mindless, reasonless, senseless
not marked by the use of reason
"mindless violence"
"reasonless hostility"
"a senseless act"
2. reasonless
not endowed with the capacity to reason
"a reasonless brute"
3. causeless, reasonless
having no justifying cause or reason
"a senseless, causeless murder"
"a causeless war that never had an aim"
"an apparently arbitrary and reasonless change"
Source: WordNet® (An amazing lexical database of English)
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