The Spanish word 'ola' meaning 'wave' comes from the French word 'houle', which refers to wave motion. This is a relatively straightforward borrowing, where the French 'h' was dropped (as often happens in Spanish), and the French 'ou' sound evolved into the Spanish 'o' sound.

Some related Spanish words include 'oleaje' (wave motion or swell), 'oleada' (surge or wave of something), and 'ondular' (to wave or undulate). These words all relate to the concept of wave motion and share similar patterns of usage.

While not directly related etymologically, English speakers might find it helpful to know that the word 'undulation' (wave-like motion) and 'swell' convey similar meanings. The English word 'roll' (as in rolling waves) can also help remember the meaning of 'ola', though they're not etymologically related.