The phrase "is immoral" can be expressed in a variety of ways, depending on the context and tone. Some alternatives could include: "is unethical," "is improper," "is wrong," "is sinful," "is indecent," "is corrupt," "is unprincipled," "is disreputable," "is evil," "is nefarious," "is wicked," "is depraved," "is viceful," "is degenerate," "is decadent," "is licentious," "is debauched," "is perverse," "is abhorrent," and "is reprehensible." Each of these synonyms conveys a slightly different shade of meaning, but all share the common thread of denoting behavior or actions that go against accepted moral or ethical standards.