Thunder  —n. 1 loud noise caused by lightning and due to the expansion of rapidly heated air. 2 resounding loud deep noise (thunders of applause). 3 strong censure or denunciation. —v. 1  (prec. By it as subject) thunder sounds (it is thundering; if it thunders). 2 make or proceed with a noise like thunder. 3 utter (threats, compliments, etc.) Loudly. 4 (foll. By against etc.) Make violent threats etc. Against.  steal a person's thunder see *steal.  thundery adj. [old english]