This is the 949th most frequent Korean word.
최초
"최초" means "the first" or "the very first."
Here, '최초' is used as a noun modifier indicating 'first' or 'initial' to describe the first occurrence of human spaceflight.
인류의 최초 우주비행은 1961년에 이루어졌다.
The first human spaceflight took place in 1961.
In this sentence, '최초로' acts as an adverb indicating 'for the first time,' modifying the action of developing technology.
그는 최초로 그 기술을 개발한 과학자였다.
He was the first scientist to develop that technology.
'최초' is utilized as an adjective here, signifying 'first' to describe the initial product released by the company.