What is a front kick? I suspect the answer someone will give depends quite a bit on who they are and what use they may (or may not) have for a front kick.
What do I think a front kick is? A general purpose tool for kicking your partner (in sparring) or your opponent (in a fight). My definition describes who I am (someone who coaches a general martial art – Mo Duk Pai) and what use I have for a front kick (sparring and self defense.)
The fun part for me about questions like these is where they lead. I find they often lead you directly to the core philosophy of what you are doing. In that case, that means what you think a front kick is (if you are a martial artist) depends a lot on what the goals of your martial art are. In other words, how you define what a front kick is will define what kind of a martial artist you are.