onrush vs military operation

onrush and military operation both are nouns.

Word	Noun	Adjective	Verb	Adverb
onrush	Yes	No	No	No
military operation	Yes	No	No	No

As nouns, military operation is a hypernym of onrush; that is, military operation is a word with a broader meaning than onrush:

onrush: (military) an offensive against an enemy (using weapons)
military operation: activity by a military or naval force (as a maneuver or campaign)

Other hypernyms of onrush include operation.

onrush (noun)	military operation (noun)
(military) an offensive against an enemy (using weapons)	activity by a military or naval force (as a maneuver or campaign)
a forceful forward rush or flow