I've seen A8-A2 typically referred to as A-rag in general, but it depends heavily on position and number of players at the table, blind levels and stack size if in a tourney, etc. The more players at the table, the more likely it is that somebody has a better Ace.
HU, even A2 is strong and likely to be the best hand, but A2 UTG at a full table is junk and should be folded pre-flop. However, if you've just taken a beat and you have 2-3BB UTG with A2, you should be pushing and hoping for the best.
I would consider even AJ/AQ as A-rag if you're in the BB with say 25-30 bigs in a typical tourney, there's a raise from EP, two callers, a 3-bet from the button, and a cold 4-bet shove from a tight SB that will cost you your entire stack to call.