Saftey questions about Vodka

Hey guys I dont drink much so i know very little, whenever me and my friend hangout we have a bit of a drink and we had bought a bottle of absolute vodka, over time we have drunk half of it and its been sitting on my shelf under a hat for months now, im just checking that it is still safe to drink? its been opened and half drunk and been sitting on my shelf (lid on) for months now