An air freshener is any of a variety of devices which contain substances which neutralize or mask unpleasant odours.

They don't actually. The bacteria on the skin break down proteins in sweat into acids which are responsible for the foul smell.

To reduce the growth of bacteria and unpleasant odours. CC ka ay? hahaha

The plural of odour is odours.

As in "there are strange odours coming from the room".

The Australian Drinking Water Guidelines statr that societys drinking water must be safe for human consumption, as well as clear, colourless, well aerated and shouldn't have unpleasant tastes or odours.