The term 'be on the same wavelength' is a phrase used to describe two people who are in agreement or understanding with each other. The crossword solutions for this phrase are AGREE (5 letters), ATTUNED (7 letters), and ATTUNES (7 letters). AGREE is a verb meaning to accept, concur, or consent to something. ATTUNED and ATTUNES are both verbs meaning to bring into harmony or adjust to a certain frequency. Therefore, the three solutions all refer to the idea of being in agreement or understanding with someone else.