The seaside is the land beside the sea, especially as a place to visit. Go to the seaside, a seaside town, a day at the seaside.
It is British and means the holiday coast rather than the coast as geography, which is why nobody says a ship ran aground at the seaside. The seaside holiday was built by the railways, and the towns that grew for it still look like it.
1nounseasideThe land beside the sea, especially as a place to visit.
“Every summer we spent a week at the seaside, building sandcastles.”
seaside is a place.
Sea plus side, in Middle English. The holiday sense grew with the railways in the nineteenth century.
Middle English
see-syde
English, today
seaside
From Middle English see-syde, sey-syde, see syde, se side, equivalent to sea + side. Compare waterside.
Etymology from Wiktionary, CC BY-SA