#trimester  a period of three months; especially one of the three three-month periods into which human pregnancy is divided
  supertype:  time_period__period__period_of_time  an amount of time; "a time period of 30 years"; "hastened the period of his recovery"
  subtype:  first_trimester  second_trimester  third_trimester
  part of:  gestation_period__gestationperiod__gestation  the period during which an embryo develops (about 266 days in humans)

No statement uses or specializes trimester; click here to add one.