What's "phobia" mean and when's it used?

Native speaker’s answer
Rebecca
"Phobia" is a noun, and it means an extreme, irrational and usually inexplicable fear or aversion to something. Although, sometimes it's used in a joking way and may not be diagnosed as an actual phobia. Someone might just be very scared of something. So you can use if you're extremely scared of something and can't interact or be close to it. One could also replace the word "phobia" with "fear." Ex: I have a phobia of heights, so I'll never go sky-diving. = I have a fear of heights, so I'll never go sky-diving. Ex: I wanted to become a doctor, but I realized I have a phobia of needles. So that wouldn't work out.