Pronunciation: (u-bak'), [key]
1. toward the back.
2. Naut.so that the wind presses against the forward side of the sail or sails.
3. taken aback, surprised and disconcerted: I was taken aback by his harsh criticism.
1. (of a sail) positioned so that the wind presses against the forward side.
2. (of a yard) positioned so that its sail is laid aback.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.