Entry 1 sense Webster, 1913 Whereupon /wĕr'-əp-än'/ · Where·up·on · IPA /ˌ(h)wɛrəˈpɑn/ 01 adv. Upon which; in consequence of which; after which. 1. Upon which; in consequence of which; after which. “The townsmen mutinied and sent to Essex; whereupon he came thither.” — Clarendon.