To define yourself in one word is hard if you are afraid your personal brand will be forever tagged -
unless it is a core value 
The critical thinking is interesting...one is the first word that came to mind? Is that the one you stick with or do you think of another word? Is that word the same one people close to you would choose?
Mine word is
passion and pretty sure many close to me would say the same. What is your word? Post it here and feel free to explain...