• (colic) Consistent pattern of crying in a healthy infant between 3 weeks and 3 months of age. Often defined as lasting 3 hours a day more than 3 days a week for at least 3 weeks in a row.
  NICHD Pediatric Terminology
  U.S. National Cancer Institute, 2021
• Paroxysms of irritability, fussing or crying that starts and stops without obvious cause in an infant up to four months of age without failure to thrive. Episodes last three or more hours per day for at least three days per week for at least on week.
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• Infantile colic is defined as paroxysms of uncontrollable crying or fussing in an otherwise healthy and well-fed infant aged <5 months. The duration of crying is >3 hours per day, and >3 days per week, for at least 3 weeks. The crying typically starts in the first weeks of life and ends by 4 to 5 months of age.
  Epocrates
  Athenahealth, Inc., 2019