Meaning of “high” - Learner’s Dictionary

high

noun [ C ] uk us /haɪ/
LARGE AMOUNT/LEVEL

the top amount or level that something reaches:

Computer ownership has reached an all-time high (= more people own computers than ever before).
EXCITEMENT

a feeling of excitement or happiness:

[ usually singular ] The players are still on a high from their last match.

(Definition of “high noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)