The Collaborative International Dictionary of English v.0.48:
Alongside \A*long"side`\, adv. Along or by the side; side by side with; -- often with of; as, bring the boat alongside; alongside of him; alongside of the tree. [1913 Webster]WordNet (r) 3.0 (2006):
alongside adv 1: side by side; "anchored close aboard another ship" [syn: aboard, alongside]