Definition of "Jellyby"

My mother, devoted to music, was a Jellyby. Strictly brought up, straight backed, never careless of her person, but still as to her children, a Jellyby.

1992, Bernard Shaw, Rebecca Swift, Letters from Margaret: correspondence between Bernard Shaw and Margaret Wheeler 1944-1950

Chuck Collins, a great-grandson of Oscar Mayer, is a rare non-fictional example of someone who gave away all his assets during his lifetime—a half-million-dollar inheritance, which he donated to charity nearly twenty years ago. […] He now has a daughter, who does not live like a Jellyby.

2005, American Society of Magazine Editors, The Best American Magazine Writing 2005, page 360