Hi,native English speakers?

I wooder if you can figure out the meaning of a new word by its formation.like "recollection" , would you consider with the context that a second collection means "to remember" ? And will you be assured without referring to dictionary？if "recollection" is too easy,then how about "complexion","countenance" and "catastrophe" ?To be honest ,I am being troubled by the enormous vocabulary of English.I am a Chinese.As to Chinese, only about 3000 characters can make you a mature language user, because almost all the vocabulary of modern Chinese are made up of those characters, and dictionary is only necessary to the students of primary schools and junior high schools . But to English, it seems ten thousand of words is far from enough.HOW MUCH vocabulary is sufficient to an English user?