Roamer is a Role in Dota 2
Roamers don't stay in lane, instead they will jump from lane to lane ganking and assisting in ganks
The following heroes are some of the heroes suitable for the Roaming role:
Enchantress
Lion
Nyx Assassin
Vengeful Spirit
For a full list of Roamers, see:
Dota 2 Roaming Heroes