IPA: /ˌɛkskləˈmeɪʃən/
KK: /ɛkˈskleɪməˌʃən/
A sudden and strong expression of emotion or feeling, often marked by a loud voice or special punctuation.
She let out an exclamation of surprise when she saw the gift.
Exclamation is formed from "ex-" (meaning out) and "clamare" (meaning to shout or cry). The word describes a shout or cry that comes out suddenly, often expressing strong emotion.
Think of someone 'shouting out' ('ex-') in surprise or excitement — that's what an exclamation is.