IPA: //ˈɡraʊndˌswɛl//
KK: /ˈgraʊndˌswɛl/
A large and sudden increase in support or opinion from a group of people, often seen in social or political contexts.
The new policy was met with a groundswell of support from the community.
Groundswell is formed from "ground" (from Old English "grund", meaning the bottom or foundation) and "swell" (from Old English "swellan", meaning to grow or increase). The word describes a rising or increasing wave of support or opinion from the foundation of a community or group.
Think of the 'ground' as the foundation and 'swell' as something that grows — a groundswell is like a wave of support that rises from the community's foundation.
No commonly confused words.