What is actually meant by the "shadowed forest"?

The dark forest is a metaphor for everything that Dante thought was wrong in 1300. This could include inner confusion and sin, the necessary imperfection of the world (as opposed to Paradise and God), political corruption, the absence of true authority, the bad behavior of the Pope, etc. Redemption is associated with struggle, in this case the struggle uphill, which is made impossibly difficult by the continual temptations of sin. The leopard is thought to symbolize lust, the lion pride, and the she-wolf avarice. The identity of the greyhound has been widely disputed: Christ, Dante himself, the Holy Roman Emperor, and Dante's benefactor Cangrande della Scala are some candidates. Since Dante strongly supported the imperial claim to authority, it seems most likely that the greyhound is the Holy Roman Emperor, Henry VII (elected in 1308, probably before the Inferno was written, but after it "took place.")