By doing just what you are doing!

- asking my mother and then all my teachers, and then dictionaries and grammar books as I grew older.
When I reply, it's easier for me to quote the definition from a dictionary because they have the meaning of a word expressed so much more succinctly than I could come up with off the top of my head.
I remember being flummoxed at the age of 5 and asking my mother the meaning of the expression, "There is no substitute for quality." (The slogan for Arnott's Biscuit Company in Australia). I couldn't grasp that level of abstraction.
I also recall asking a science teacher when I hit high school, 'what's the difference between a fluid and a liquid'. Even she asked me to leave it with her while she "thought about it".