1. To arrange in a line or so as to be parallel: align the tops of a row of pictures; aligned the car with the curb.
2. To adjust (parts of a mechanism, for example) to produce a proper relationship or orientation: aligning the wheels of a truck.
3. To ally (oneself, for example) with one side of an argument or cause: aligned themselves with the free traders.

1. To adhere to a prescribed course of action.
2. To move or be adjusted into proper relationship or orientation.

[French aligner, from Old French : a-, to (from Latin ad-; see ad-) + ligne, line (from Latin līnea; see line¹).]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.