both banks; both shores
Refers to the two sides of a river, stream, or similar body of water. Often used in geographical descriptions, news reports, or literary contexts.
This bridge connects both banks of the river.
Cherry trees are planted on both banks of the river.
Houses on both banks were damaged by the flood.
Cherry blossoms line both banks of the river.
対岸 means the opposite (far) bank as seen from where you stand, whereas 両岸 means both banks considered together.
cross-strait relations
Standard kanji spelling; the reading りょうぎし is rare and not normally used in modern Japanese.
Compound of 両 (both) and 岸 (bank, shore). The reading りょうぎし is a rare alternative using the older kun'yomi for 岸.