The phrase "is in tune" refers to something that is well-adjusted, harmonious or synchronized with its surroundings. Some possible synonyms for this phrase include "aligned," "accordant," "in sync," "compatible," "coherent," "concordant," "congruent," "consistent," and "harmonized." Each of these options highlights a slightly different nuance or aspect of being in tune, but all convey a sense of balance, agreement, or unity. Whether applied to musical instruments, relationships, or organizational goals, being in tune is an important factor in achieving success and satisfaction. So whether you choose to say "aligned" or "congruent," the important thing is to ensure that everything is in harmony.