Middle English: via Old French from Latin instantia ‘presence, urgency’, from instare ‘be present, press upon’, from in- ‘upon’ + stare ‘to stand’. The original sense was ‘urgency, urgent entreaty’, surviving in at the instance of. In the late 16th century the word denoted a particular case cited to disprove a general assertion, derived from medieval Latin instantia ‘example to the contrary’ (translating Greek enstasis ‘objection’); hence the meaning ‘single occurrence’