The term IN ___ (TOGETHER) can be filled in with three different words: UNISON, TANDEM, and SYNC. UNISON is a word that means 'in complete agreement or harmony, ' while TANDEM is a word that means 'two people or things working together.' Lastly, SYNC is an abbreviation for the word 'SYNCHRONIZE, ' which means to 'make two or more things happen or occur at the same time.' All three of these words refer to the idea of two or more people or things working together in harmony.