Top, apex, are two possibilities.
it means to sen in something
The word you are looking for is "peak" or "summit."
Summit
Peak
zenith.
Zenith.
poo oh there isn't one no, there isn't. oh wait, summit.
A three letter word for a summit = Top.
The word "reply" means the same as respond.
The word summit is a noun. Some words that can be used in place of summit are top, crowning point, crest, crown, and zenith. Also on the list are capstone, peak, roof, and pinnacle.
Surprised almost means the same as startled.
"Similar" is a word that means nearly the same as "like."