Unilateral is an adjective that means performed by only one person, group or country. 

The Latin word latus (LA toose) means ‘side.’ By adding the prefix U-N-I meaning ‘one, ‘ we get a word that means ‘taking place on only one side.’ Our word of the day is often used in the context of conflict between nations. Here’s an example:

Ending the agreement between the countries in a unilateral fashion wasn’t such a good move. When things happen in such a one-sided way, there are often unpleasant repercussions.