septenary vs septet

septenary

• A group of seven things. 

• A period of seven years. 

• The seven notes of the diatonic scale. 

• Of seventh rank or order. 

• Consisting of or containing seven. 

• Lasting seven years; continuing seven years. 

septet

• A set of seven lines. 

• A group of seven musicians. 

• A composition for a group of seven musicians.