na-adjective
preliminary; preparatory
Used for something done in advance as preparation or as a preliminary step. Often appears in formal or written contexts.
予備的な調査を行った。
We conducted a preliminary investigation.
これは予備的な段階に過ぎない。
This is merely a preparatory stage.
Formed from 予備 (yobi, 'reserve, preparation') + the adjectival suffix 的 (-teki, '-like, -al').