listen in

verb

listened in; listening in; listens in

intransitive verb

1

: to tune in to or monitor a broadcast

2

: to listen to a conversation without participating in it

especially : eavesdrop

listener-in

ˌli-sᵊn-ər-ˈin 

ˌlis-nər-

noun

Synonyms of listen in

• eavesdrop (on)
• hear
• monitor
• spy
• overhear

Examples of listen in in a Sentence

it's not polite to listen in on other people's private conversations

Recent Examples on the Web

For the past six years, Project CETI (Cetacean Translation Initiative) has been listening in on the chatter of sperm whales in the Eastern Caribbean off the coast of the island of Dominica. — Laura Baisas, Popular Science, 22 July 2026

Compared with earnings calls that Lu listened in on last year, wherein diversification away from China was a key order of business, that motivation has largely petered out in 2026. — Kate Nishimura, Footwear News, 21 July 2026

Researchers have used the EAR to listen in on postpartum women, couples, Americans after 9/11, and young athletes. — Shayla Love, New Yorker, 8 July 2026

Seated near the senators, a woman in a crisp white uniform appears to listen in, her hands folded neatly in her lap. — Karissa Waddick, USA Today, 25 June 2026

Word History

First Known Use

1905, in the meaning defined at sense 1

Kids Definition

listen in

verb

1

: to listen to a broadcast

2

: eavesdrop