dildo

Unclear; possibly an alteration of English diddle. Compare the use as an expressive nonsense syllable in often sexual songs and the spelling dil doul, found in e.g. The Maids Complaint for want of a Dil Doul, a song in the library of Samuel Pepys. Unlikely to be related to Italian diletto (“delight”) or Latin dīlātō (“to open up, spread”), often cited etymologies.

Related to other nonsense syllables like dido and diddle(-diddle), which similarly developed sexual senses. Found since at least the 1500s, often in contexts where allusion is being made to the sexual sense (above). Possibly influenced by Middle English dildoun (“darling, pet”), early modern English dildin (“sweetheart”); compare Old Norse dilla (“to lull”), dillindo (“lullaby”).