Not counting Treehouse of Horror episodes or dream/fantasy sequences, her first real word was "Daddy" although no one heard it. As for as the family knows, her first word in the series was "Yah" said in Season 20's Coming to Homerica, although she also had her 'first' word at the end of The Simpsons Movie in 2007 when she said "Sequel".
She has officially spoken four times.
Her official first word was "Daddy" from Season Four's Lisa's First Word, but no one heard her, so as far as the family knows her first word was "Sequel" which she said at the end of The Simpsons Movie, however, in the series, Marge claims her first word was "Yah", spoken in the last episode of Season 20, Coming to Homerica.
She spoke full sentences [granted not grammatically perfect] in the second episode of Season 28, Friends and Family, in a flashback during a family argument at a therapist's office, she says "Maggie talk. Maggie talk. No one listen. Maggie never talk again."
She also said Daddily-Doodilyin Season Seven's "Home Sweet Homediddly-Dum-Doodily" but no one acknowledged she said anything so evidently it was just heard as baby gibberish and not actual speech.
The unibrowed baby.
maggie simpson
Bart, Lisa and Maggie
Maggie Simpson.
There are several little girls on The Simpsons... Lisa, Maggie, Janey, Sherri, Terri, Jessica
And Maggie Makes Three | S06E13
lisa(simpsons)
Yes.Yes, she was just learning to walk.
The baby on the Simpsons is Maggie Simpson.
No. She has said three words. Daddy - Which no one heard. Sequel- at the end of The Simpsons Movie & Yah- in Homer to America.
Maggie Simpson
Maggie Simpson
No Maggie is
The unibrowed baby.
Baby Gerald. x
Maggie Roswell.
Marge and Homer Simpson