noun
offshore wave; deep water wave
Refers to waves in the open sea, away from the shore. Often used in nautical or oceanographic contexts.
沖波が高く、漁船は港に戻った。
The offshore waves were high, so the fishing boats returned to port.
天気図によると、明日は沖波がさらに強まる見込みだ。
According to the weather map, offshore waves are expected to become even stronger tomorrow.
Compound of 沖 (offshore, open sea) and 波 (wave). The reading おきなみ is a straightforward combination of the kun'yomi readings of the two kanji.