WMD vs weapon

WMD and weapon both are nouns.

Word	Noun	Adjective	Verb	Adverb
WMD	Yes	No	No	No
weapon	Yes	No	No	No

As nouns, weapon is a hypernym of WMD; that is, weapon is a word with a broader meaning than WMD:

WMD: a weapon that kills or injures civilian as well as military personnel (nuclear and chemical and biological weapons)
weapon: any instrument or instrumentality used in fighting or hunting

Other hypernyms of WMD include arm, weapon system.

WMD (noun)	weapon (noun)
a weapon that kills or injures civilian as well as military personnel (nuclear and chemical and biological weapons)	any instrument or instrumentality used in fighting or hunting
	a means of persuading or arguing