My first word was 'Hello' when I was a baby, very young actually...
But the first German word I learned was actually a phrase...
"Bück dich befehl ich dir" Taught to me by my perverted twin brother.... Actually, the translation isn't all that perverted, it simply means "Bend down I command you" Bück dich was all I could remember that young tho....
My first Japanese words were "Takai Yama!!" Or Tall Mountain, which my mom taught me. So, what were your first words???