Shmoop lucked out on this one, because Natalie Babbitt did the work for us, spilling the beans on what her characters' names mean. We'll let her take the wheel for a minute:
In most of my books, the characters' names have secondary meanings that the reader doesn't have to know. In Tuck Everlasting, Winnie's last name—Foster—means "forester." The name Tuck came from a thesaurus and an old dictionary. I wanted a name that meant life and was only one syllable. When I looked it up in my old dictionary, I found that tuck meant life. (Source.)
So the names aren't necessary to understanding the book, but they're definitely an added bonus. Icing on the cake, we'd say.
Sometimes the lack of name can be telling, too. Most importantly in Tuck Everlasting, we don't know the name of the man in the yellow suit. Check out our "Character Analysis" of the slime ball to find out why.