phlegmatic

showing little emotion

Arnold is truly noble, remaining reserved until an issue of significance arises, but Walter is simply phlegmatic: he doesn't have the energy or inclination to care about anything.

English, in our passion for daily excitement, might call her phlegmatic, but we should call her so unjustly.

One of the psychologists in Solar Defence had termed Hunter phlegmatic, which is to say lazy and sluggish.

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