So my delinquent roommate has informed me, somewhat adamantly, that a word exists to describe the set of classmates that went to school with someone during their entire tenure at a school. To elaborate, I went to Butler from 02-06, so this word would encompass the folks that were seniors in '02 to those that were freshman in '06. (seven classes in all)

Can you smiths please help me find this word!?

I am new to the boards here, so go easy on me if this is really entry level wordsmithery. Thanks ahead of time!