Unwarranted
adjective
incapable of being justified or explained
Similar: indefensible, insupportable, unjustifiable, unwarrantable
adjective
lacking justification or authorization
“desire for undue private profit”
Similar: undue, unjustified
adjective
without a basis in reason or fact
“baseless gossip”
Similar: baseless, groundless, idle, unfounded, wild