What are the uses of lexicon?

The professor used a Greek lexicon to decipher the text.I am in the Arabic lexicon.

I am in the Arabic lexicon.

I looked up the flower I saw and did not recognize in my flower lexicon

Using " Has " is referred a past tense. Such as: He has taken the garbage out already. Using " Is " for example is referred a Present tense. Such as: He is taking out the garbage.

A drawbridge allows welcome guests into a castle to cross the moat(a trench of water that goes around the perimiter of the castle)