The Spanish verb 'orillar' comes from the noun 'orilla' meaning 'edge' or 'shore', combined with the verbal suffix '-ar'. The noun 'orilla' itself derives from Latin 'ora' meaning 'edge' or 'border' plus the Latin diminutive suffix '-illa'. This combination literally meant 'little edge' before evolving into the modern Spanish word for 'edge' or 'shore'. The verb 'orillar' thus literally means 'to make or form an edge' or 'to border'.

The most obvious related Spanish word is the noun 'orilla', which is much more commonly used than the verb 'orillar'. While 'orilla' specifically refers to an edge or shore (like the shore of a lake or the edge of a piece of cloth), the verb 'orillar' has taken on the active meaning of creating or forming such an edge.

While there aren't any common English words directly related to 'orillar', English speakers might find it helpful to know that the Latin word 'ora' (meaning edge or border) appears in some English scientific terms. For example, 'oral' (relating to the mouth, which is an opening or edge of the body) and 'aurora' (the dawn, literally meaning 'dawn's edge') share this ancient root, though their meanings have diverged significantly from the Spanish 'orillar'.