A person who fights or struggles tenaciously; a determined fighter. Despite the odds, she was a battler who never gave up on her dreams.
In Australian and New Zealand informal usage, a person who works hard and makes a modest living despite difficulties. He's a real battler, always finding a way to make ends meet for his family.
A competitor, especially a racehorse or sports player, of modest talent who competes gamely and with determination. The colt was considered a battler who could surprise the favourites on a wet track.
Informal (chiefly Australia and New Zealand) A habitual gambler who persists despite frequent losses. He spent every Saturday at the track, just another battler hoping for a big win.