rush (n.2) Look up rush at Dictionary.com
late 14c., from rush (v.). Sense of "mass migration of people" (especially to a gold field) is from 1848, American English. Meaning "surge of pleasure" is from 1960s. Rush hour first recorded 1888.
rush (v.) Look up rush at Dictionary.com
mid-14c. (implied in rushing), "to drive back or down," from Anglo-French russher, from Old French ruser "to dodge, repel" (see ruse). Meaning "to do something quickly" is from 1650s; transitive sense of "to hurry up (someone or something)" is from 1850. Football sense originally was in rugby (1857). Fraternity/sorority sense is from 1896 (originally it was what the fraternity did to the student).
rush (n.1) Look up rush at Dictionary.com
"plant growing in marshy ground," Old English resc, earlier risc, from Proto-Germanic *rusk- (cf. Middle Low German rusch, Middle High German rusch, West Frisian risk).

Old French rusche probably is from a Germanic source. Used for making torches and finger rings, also strewn on floors when visitors arrived; it was attested a type of "something of no value" from c.1300.