The story
- Latin · derived fromīnsistere
- Middle French · borrowed frominsister
- English todayinsist
Partly from Middle French insister, from Latin īnsistere; and partly from a back-formation from insistence. Compare typologically from the same PIE root Bulgarian настоявам (nastojavam), Russian наста́ивать (nastáivatʹ).
Etymology from Wiktionary, CC BY-SA 4.0.