The Spanish word 'coronilla' comes from the Spanish word 'corona' (meaning 'crown') combined with the diminutive suffix '-illa', literally meaning 'little crown'. The Spanish 'corona' traces back to the Latin word 'corona' (also meaning 'crown'), which ultimately derives from the Ancient Greek word 'κορώνη' (korone), meaning 'curved object' or 'crown'.

The diminutive suffix '-illa' is commonly used in Spanish to form words indicating something smaller or more endearing than the base word. In this case, it transforms 'corona' (crown) into 'coronilla' (little crown).

The most obvious related Spanish word is 'corona', meaning 'crown'. This is the base word from which 'coronilla' is derived. While 'corona' refers to a full-sized crown or anything crown-like, 'coronilla' specifically refers to something smaller or crown-like in shape, such as the crown of the head or a small coronet.

Several English words share the same Greek-Latin ancestry as 'coronilla'. The most direct cognate is 'crown', which comes from the same Latin 'corona'. Other related English words include 'corona' (as in the sun's corona or, more recently, the coronavirus), 'coronal' (relating to a crown), and 'coronet' (a small crown). Notice how these words all maintain some connection to the original meaning of something curved or crown-like.