Unimpassioned is an 11-letter word meaning EMOTIONLESS, and can be broken down into two words: uni- and -passioned. The prefix 'uni-' means one or single, and the suffix '-passioned' means without passion or emotion. Therefore, the term 'unimpassioned' can be used to describe someone who is without emotion or feeling. The term can also be used to describe something that is done without emotion or feeling. A similar 5-letter word is 'SOBER, ' which means not affected by alcohol or drugs and also implies a lack of emotion.