The term comes from the Latin fons, "spring of water," and designates a receptacle for baptismal water. Fonts in the early church were pools or sunken basins, often in the shape of a cross, in which candidates were immersed in running water. Many fonts remained large even after infant baptism became the norm, but they were raised above ground for convenience. Eventually the typical font was the size of a wash basin, and even adult candidates were baptized by pouring a little water on their heads. The ancient practice never died out, however, and the BCP lists immersion as a method of baptizing. Today some new or renovated church buildings have a large font, suitable for immersion, located where the people can easily see it or gather around it.
Glossary definitions provided courtesy of Church Publishing Incorporated, New York, NY,(All Rights reserved) from "An Episcopal Dictionary of the Church, A User Friendly Reference for Episcopalians," Don S. Armentrout and Robert Boak Slocum, editors.