A starch extracted from the sago (and other tropical) palms that is processed into flour, meal and pearl sago, which is similar to tapioca. South Pacific cooks frequently use sago for baking and for thickening soups, puddings and other desserts. In the Orient and in India it's used as a flour and in the United States it's occasionally used as a thickener.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.