Bitcoin is money. That's the whole point of bitcoin, is to be able to use it as a means of payment. If you want to get "technical", Wikipedia describes money as "Money is any object or record, that is generally accepted as payment for goods and services and repayment of debts in a given country or socio-economic context." Bitcoin certainly falls within those boundaries.

At this point, Bitcoin is not stable enough to be used as a mainstream currency, so the majority of Bitcoin is just involved in stock-like transactions, but the intended end result of Bitcoin is to be able to use it as a currency.