Having four phases or conditions; in gas-engines, four-cycle.
The Century Dictionary (Public Domain)
Use "four-phase" in a sentence
"Importantly, the four-phase program trains you to gauge your personal tolerance for carbohydrates, so that you can tailor a program that not only fits you to a T but also enables you to permanently banish excess pounds and maintain improved health indicators."
"Gonzalez-Herrero and Pratt created a four-phase crisis management model process that includes: issues management, planning-prevention, the crisis, and post-crisis (Gonzalez-Herrero and Pratt, 1995)."
"For example, his infomercial claims that dieters who complete “Phase 4” of the four-phase protocol can eat anything they want, but the book says that they must eat “only 100% organic food” and avoid brand name food, fast food, or food served by regional or national restaurants."