what does "zenith" mean

its on page 205.

i have to do an A-Z book on scarlet letter and i was picked to do M-Z and the only one i realy need help with is Z.

in the book it uses the word zenith and i looked the word up and it says higher above the observer..and a bunch more having to do with stars... and i just cant figure out what i stands for or decode it to where it sounds more up to date with todays english.

ive tryed other websites and none of them realy covered its meaning.