The Spanish word 'idóneo', meaning 'suitable' or 'appropriate', comes directly from the Latin word 'idoneus', which had the same meaning. This is a straightforward inheritance where both the form and meaning have remained remarkably stable from Latin to modern Spanish, with only minor phonetic adaptations to fit Spanish pronunciation patterns.

There aren't many common Spanish words that are directly related to 'idóneo', as it stands somewhat isolated in modern Spanish vocabulary. However, you might encounter it frequently in formal or academic contexts, particularly in phrases like 'candidato idóneo' (suitable candidate) or 'momento idóneo' (appropriate moment).

While English doesn't have any common direct descendants from Latin 'idoneus', the word 'idoneous' exists as a rare, technical term meaning 'appropriate' or 'suitable'. However, since this is such an uncommon word in English, it might be more helpful to remember 'idóneo' by associating it with more familiar English words like 'ideal' or 'appropriate', even though they're not etymologically related.