The term 'opposite of relaxed' can be described by two words: TAUT (4 letters) and ANTSY (5 letters). TAUT is an adjective that means 'stretched tight, ' and it is often used to describe a rope or a surface that has been pulled tight. ANTSY is an adjective that means 'restless or nervous, ' and it is often used to describe someone who is feeling anxious or impatient. Together, these two words provide a good description of the opposite of relaxed.