Lady Gaga wowed the Grammy audience with her multimedia song and dance tribute to David Bowie, but the son of the late British singer seemed less than impressed.

Film director Duncan Jones, the son of Bowie and his first wife Angie, made a cryptic post on Twitter following Monday’s Grammy awards show in which he shared a dictionary definition of the word “gaga.”

“‘Overexcited or irrational, typically as a result of infatuation or excessive enthusiasm; mentally confused.’ Damn it! What IS that word!?” Jones wrote.

Gaga’s medley of Bowie’s biggest hits was punctuated by a torrent of flashing multicolored lights and images projected on a large screen behind her, including a closeup of her face adorned in “Aladdin Sane: makeup — a nod to one of Bowie’s personas — with a spider crawling over her nose.

The tribute to Bowie, who died in January of cancer, was widely seen as one of the highlights of the Grammy Awards in Los Angeles, and was one of the most-discussed moments of the show on social media.

Jones’ comments triggered outrage and sympathy. Twitter user Lady Teapots said it was “cruel and mean spirited to attack Lady Gaga who gave her all to honor and entertain” while Darcy Bennett tweeted, “Surely the man is entitled to his opinion. especially considering it’s about his father.”

Gaga on Tuesday limited herself to giving Instagram thanks to those who made the tribute possible, including fashion designers such as Marc Jacobs who recreated some of Bowie’s signature looks during his glam rock phase of the 1970s.

During the weekend Gaga had showed off pictures of a new tattoo on her ribcage of Bowie with a lightning bolt across his face.