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large or relatively large in number or amount or extent or degree; "a considerable quantity"; "the economy was a considerable issue in the campaign"; "went to considerable trouble for us"; "spent a considerable amount of time on the problem"
causing fear or anxiety by threatening great harm; "a dangerous operation"; "a grave situation"; "a grave illness"; "grievous bodily harm"; "a serious wound"; "a serious turn of events"; "a severe case of pneumonia"; "a life-threatening disease"