The longest planning unit in a training program, usually six months to a year, made up of several mesocycles aimed at one outcome.
It is the top of the three-level stack: microcycle (a week), mesocycle (three to six weeks), macrocycle (a season or a year). For an athlete it ends at a competition. For a general client it ends at whatever date actually exists in their life, a wedding, a trip, a first powerlifting meet.
A worked example for a client who wants to deadlift 180 kg by June, starting in January: January to February a hypertrophy mesocycle at 8 to 12 reps, March to April a strength mesocycle at 3 to 5 reps, May a peaking mesocycle at 1 to 3 reps, then a taper week and the attempt.
Most trainers never write one down, which is why programs drift. The macrocycle is what stops January and April from looking identical.