This is the 4170th most frequent Japanese word.
一大
"一大" means "one large" or "a major."
The term '一大' is used here to indicate 'a major' or 'significant,' describing the importance of the step in relation to the project.
このプロジェクトは一大ステップとなります。
This project becomes a major step.
'一大' conveys 'great' or 'major,' emphasizing the significant influence of the invention on society.
彼の新しい発明は社会に一大の影響を与えました。
His new invention had a major impact on society.
In this sentence, '一大' highlights the importance or prominence of the event.