It kicked off on Thursday night (11 July) after Azealia described Lily's husband Sam Cooper as "ugly" while responding to someone on her timeline.
Azealia later directly tweeted at Lily: "Your husband looks like a thumb."
Lily, however, wasn't going to stand for that, and tweeted a response, though said she wasn't going to bother sending it directly via @ to her intended recipient.
The 'Smile' singer described Azealia as a "one hit wonder", and added: "And my husband ? Don't go there bitch Or your totally unnecessary security detail may actually have something to worry about."
She also jokingly added: "Ps, everyone needs thumbs."
And my husband ? Don't go there bitch Or your totally unnecessary security detail may actually have something to worry about #wannabe— lilyrosecooper (@lilyrosecooper) July 11, 2013
American rapper Azealia, who has been involved in Twitter feuds with other artists in the past, hit back saying: "LOL ill be a one hit wonder but you have ugly children."
Lily, who has two daughters, Ethel and Marnie, responded by using Azealia's middle name, saying: "Okay Amanda , whatevs. #musthaveasongcomingout."
She also later appeared to poke fun at the Twitter beef by posting a photo of a slice of roast beef, declaring: "It's official."
Will this be the last we hear of this spat?