You're most likely to come across the word unilaterally in a news report, since it's often used to describe actions taken by governments. If one country unilaterally launches an attack on another, it means the country's government does not consult groups like the United Nations or other affected countries before making the decision to attack. The Latin root, unilateralis, combines the prefix uni, or "one," with latus, "side," to make a word that means "one-sided."