coastline

noun

coast·​line ˈkōs(t)-ˌlīn 

1

: a line that forms the boundary between the land and the ocean or a lake

2

: the outline of a coast

Examples of coastline in a Sentence

The plane flew along the eastern coastline.

Recent Examples on the Web

Mogadishu rejects Somaliland’s claim to sovereignty and considers Berbera, its coastline and its resources part of Somalia. — Yinka Adegoke, semafor.com, 16 Sep. 2026

The former is the center of the Taiz Governorate, which encompasses southeastern Yemen and the Red Sea coastline recently seized by the Houthis. — David Brennan, ABC News, 16 Sep. 2026

The Rolex Swan Cup takes place every two years on the Costa Smeralda, Sardinia’s glittering northern Italian coastline, and this September a record 170 yachts will line up on a hectic start line. — Andrew Rice, New York Times, 15 Sep. 2026

Continue reading … LOST AT SEA — Dozens vanish after passenger ferry sinks as rescuers scour South Pacific coastline. — FOXNews.com, 15 Sep. 2026

Word History

First Known Use

1856, in the meaning defined at sense 1

Rhymes for coastline

• affine
• airline
• align
• aline
• assign
• baseline
• beamline
• benign
• bloodline
• bovine
• brucine
• byline

Kids Definition

coastline

noun

coast·​line ˈkōst-ˌlīn 

: the outline or shape of a coast