What does "opt-in" mean?

The property of having to choose explicitly to join or permit something; a decision having the default option being exclusion or avoidance; used particularly with regard to mailing lists and advertising.

Opt-in

adj

adj ·Rare ·Advanced level

Definitions

Adjective

1
The property of having to choose explicitly to join or permit something; a decision having the default option being exclusion or avoidance; used particularly with regard to mailing lists and advertising. not-comparable
"They set up an opt-in mailing list, so that those who wanted the notices could subscribe."

Antonyms

All antonyms

opt-out

Example

More examples

"They set up an opt-in mailing list, so that those who wanted the notices could subscribe."

Etymology

From opt + in.

Related phrases

double opt-in

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.