Once upon a time, in a galaxy far far away, Rollover IRAs were used for funds that came from (were rolled over from) a 401(k) account or a 403(b) account. All that money (including any earnings in the interim) could be rolled over into a 401(k) plan with a new employer etc.  One _could_ make a regular contribution to a Rollover IRA but once such a _commingling_ of money occurred, _none_ of the money in the Rollover IRA could be rolled over into a 401(k) account etc. In those good old days when contributions to IRAs were made by paper check and "deposit slip", one had to write a letter to the Rollover IRA custodian certifying that the IRA owner understood that the contribution would destroy forever the possibility of rolling over the money into another 401(k) etc.

All this went by the wayside a few years ago when the law changed and the distinction between Rollover IRAs and ordinary Traditional IRAs was eliminated. Commingling of IRA contributions and Rollover money from 401(k)s are permitted, and the entire IRA balance could be rolled over into a new 401(k) plan (provided the new plan accepted rollovers). However the adjectives still persist; like chili555, I too have IRAs that are still called Rollover IRA, they all have commingled funds, and if the law ever changes back, none of those IRA accounts would be eligible for rolling over into a new 401(k).