1.NounA period of time in the life of dogs, defined such that the average life expectancy of a dog in "dog years" is numerically equivalent to the average life expectancy of a human. A 4- and a 5-year-old dog are about as mature as a human of 28 to 30 years and 33 to 35 years, respectively. The most common calculation uses a ratio of seven dog years to one human year.
2.NounA unit of age relative to the species being considered, defined such that an animal's age in "dog years" is the equivalent age of a dog in calendar years.