Gillby \gi-ll-by\ as a boy's name is a variant of Gilby (Old Norse, Irish, Gaelic), and the meaning of Gillby is "estate of the hostage; blond boy".

The baby name Gillby sounds like Gillbey, Collby, Gillbie, Gilbey and Kellby. Other similar baby names are Gilley, Gibby, Gill, Gillis, Gilles, Gillon, Gillen, Gillan, Gilroy, Gilray, Gillray, Gillroy and Wellby.