The phrase "gotten a lather" is a slang term used to describe being in a state of intense emotional agitation or anger. Antonyms for this phrase would therefore include words like calm, relaxed, composed, tranquil, peaceful, and serene. These words evoke a sense of stability and emotional balance, rather than the frenzied, turbulent state implied by "gotten a lather." Other antonyms could include words like unflappable, collected, cool-headed, phlegmatic, and even-tempered. Overall, these antonyms convey a sense of emotional control and stability, in contrast to the heightened emotional state implied by "gotten a lather.