1 put in a straight line or bring into line (three books were neatly aligned on the shelf).
2 esp. Polit. (usu. foll. by with) bring (oneself etc.) into agreement or alliance with (a cause, policy, political party, etc.).
Derivatives:
alignment n.
Etymology: F aligner f. phr. agrave ligne into line: see LINE(1)
Useful english dictionary. 2012.