To opt out is to choose not to take part. Opt out of the scheme, an opt out clause, opted out entirely.
The design question behind it is who has to act: an opt out system enrols everybody unless they refuse, which is why organ donation and pensions moved to it and participation rose sharply. The opposite is opt in.
1phraseopt outTo choose not to take part.
“If you don't want your data shared, you can opt out by ticking this box.”
opt out is a refusing.
Opt plus out, from Latin optare, to choose.
From opt + out.
Etymology from Wiktionary, CC BY-SA
Practised in Phrasal Verbs