Cohorts, for the purposes of this article and site, are self-identified groups of individuals who are close enough in age to have shared and to identify with the same defining moments and events in their lives. The phrase "Baby Boomers" was coined well before most or all of us could self-identify as anything. The Baby Boom is not a cohort. It is an externally imposed generational label. So let's see what cohorts actually exist within this expansive, lack-luster title.
In a traditional sense cohorts are members of an age grade who go through a societal unit's initiation rites together. Basically this means that cohorts are people of the same age who suffered the same painful experiences as they came of age. It's the old, "hey, we went to different High Schools together" phenomenon. Just because it is an anthropological and demographic term, it does not necessarily mean that it has to apply only to people from a small village in North Africa who have their strongest sense of affiliation with the other adolescents who were circumcised at the same time as they were. You might find yourself declaring affiliation with someone you just met in an airport after small talk allows you to discover that you both saw The Tom Tom Club at Danceteria on the same night back in '82 and remember that stunning woman who had the man following her around on a leash. But there is also that earlier time period when you were an acne-enhanced 8th year 4Her somewhere west of the Wea Plains. That certainly defines a slightly different subset of people with whom you can claim age-grade affiliation informed by a particular culture. I suspect you get the idea.
A generation is a time interval for societal replacement. It's the time it takes one group of people of prime breeding age to be replaced by their children at that same age. We usually think of it as being between 20 and 30 years. Cohorts are more flexible. A cohort can be a high school class, pre-1980 proto-punkers, or indian-print wearing vegetarians who were in high school when Janis Ian's "At Seventeen" came out. You can define the term as inclusively or in as tightly constricted fashion as you like. I have a tendency to define terms in a limber fashion. Language is fluid. Constraints enable as well as limit.
So how many labels can you think of for us? Me Generation. Blank Generation. Tweeners. Jonesers. Second Wave Boomers. Trailing Edge Boomers. Do any of these sound appealing to you? Nah, me neither. I don't particularly like Late-Boomers either, but it distinguishes the unique grouping of the post-Vietnam era Boomers from the older Boomers, while still linking us to the demographic phenomenon that was the post-WWII birth boom. Baby Boom births did not peak until 1957 and arrived back at 1945 levels only after 1964.
I get really really frustrated when people don't know which definition they are using for what. Now I don't mind loose definitions, I've played fast and loose myself, it's more fun that way, but sloppy thinking is so de classe. The definitions I use on this site tend to synchronize with definitions used by governmental entities. If you are going to pigeon-hole, you might as well use THE official roost's lingo. U.S. Government publications refer to the Baby Boom as the period from 1946 through 1964. Period. End of discussion. Be very careful of people who cannot distinguish generations from cohorts. Generation X did not begin in 1960. Generation X, by definition, cannot remember the first lunar landing. People born in 1964 can and do remember. Generations tend to be official designations these days.
Cohorts tend to be less official and more malleable, and self-defined as they are more than just an age grade. The very fuzziness of the terminology appeals to many individuals. Self-definition means that we can vary the definition as needed to include or exclude weird groups or individuals as required. My home town cohort is far more inclusive in range of tolerated behavior than my acknowledge you on the street in the big city cohort, but my web cohort is a totally different beast as the potential number is essentially without limit (or at least bigger than this ol' girlie can fathom.) Basically the soft and slow (as opposed to hard and fast) rule is that cohorts have to about the same age, sort of, and affiliated through a social linkage. If you are reading this, there is a very good chance that we are in the same cohort according to someone's definition.